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3 Assessment of the Divisions Focusing on the three assessment criteria that it was requested to consider (see Chapter 1), the Panel on Electronics and Electrical Engineering presents the following assessment, outlined by division, and includes a discussion of selected specific projects. OPTOELECTRONICS DIVISION The Optoelectronics Divisionâs key projects are well chosen and focus on important and growing segments of the optoelectronics industry. The limited resources currently available do not allow coverage of all industry segments with sufficient critical mass. New funding is required in order to add other programs focused on areas of current national priorities. The scientific and technical work meets the highest standard of excellence. However, the conditions of some individual laboratories were found to be overcrowded and cluttered. Resources should be allocated to tidy up the laboratories and improve the environmental conditions so as to ensure the workersâ safety and health. Key segments of the optoelectronics industry include biophotonics, displays, lighting, lasers, optical communications, optical storage, photovoltaics (PV), terahertz technology, and quantum information. Owing to the limited resources available, the divisionâs choices are to focus on four strategic program themesâradiometry, waveform metrology, quantum information and metrology, and nanophotonic metrologyâwhich are outstanding choices given the existing resources. Calibration services are strong and should remain at the same level. Laser Radiometry Project The technical merit of the Laser Radiometry project continues to be the best in its field, among other national metrology institutes (NMIs) internationally, and has been engaged in international comparisons of laser power with Germany, Great Britain, Japan, Mexico, Russia, and Switzerland. For example, the project has set the benchmark in high- power coatings, with a demonstrated damage threshold exceeding 15 kW/cm2. A comprehensive program includes a strong theoretical effort that is modeling the optical- to-amorphous carbon/carbon nanotube interaction. This work is benchmarked with experimental results, and it has resulted in an improved understanding of the underlying photophysics of carbon nanotube (CNT) coatings, which should further broaden their application base. The researchers can do a comprehensive experimental analysis of CNT material to quantitatively determine compositionâwork that can be done on bulk and not just on isolated samples. The Laser Radiometry Project team does a remarkable amount of work with modest resources. Out of NISTâs $5 million per year of calibration income, this team accounts for 10 percent of total NIST income from calibration services. It performs approximately 300 tests per year (1.5 tests per day), with an on-time completion rate of 9
95 percent and an average turnaround time of 22 days. This is done with a modest-sized group of 5 people. The addition of new equipment, such as a state-of-the-art tunable optical parametric oscillator system, could greatly facilitate the work. Facility renovation, including updated fume hoods, is needed. Along the same lines, a better infrastructure for handling nanotubes would facilitate the CNT work. The project team also has limited access to tools such as scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), transmission electron microscopy (TEM), and atomic force microscopy (AFM) for its nanotechnology work. If the EEEL were able to add one or more of these costly items, the work of this group would be further amplified, and the resource could be made available to other groups at NIST as well. This project is well aligned with the laboratoryâs mission, providing the best traceable laser radiometry measurements. It has evolved into a more comprehensive program with the addition of the CNT theory component, and the extended wavelength capability (200 to 1,800 nm) and extended power range of the detector program (spanning orders of magnitude from hundreds of kilowatts to single photons) are a critical service to the optoelectronics industry. The availability of CNT type identification is key to developing standards for toxicity a significant problem for which this team could play a leadership role in setting rigorous standards. This should be encouraged. High-Speed Measurements Project The High-Speed Measurements project has demonstrated the groupâs capability to achieve state-of-the-art calibration of oscilloscopes in the frequency range from 110 to 400 GHz. Its covariance-based analysis technique represents a new methodology for calibrations. The project team is developing test methods, including linear optic sampling, that are very useful for the characterization of components for advanced modulation methods. These advanced modulation methods, including phase modulation and polarization multiplexing, are being used for 40 and 100 Gb/s communications system development. Software to end users who want to perform their own calibrations is also provided. Reasonable resources in equipment and space are provided for this project. However, there appears to be a serious problem with environmental stability. There are incidents of delayed programs owing to variations in the laboratory temperature that disrupt measurements and calibrations and cause them to be repeated in order to achieve the state-of-the-art results of which this group is capable. The root cause of the temperature variations seems to be problems in the chilled-water system. The project meets its stated objectives of improving the calibration capabilities and measurements of high-speed waveforms. One suggestion for a new program is to look for collaborations between the optical frequency combs and the high-speed measurements projects. In order to establish some relationships with industry to apply their techniques to component manufacturers, for example, the design of lithium niobate modulators for 40 and 100 Gb/s phase-modulated systems would be beneficial. 10
Frequency Combs Project The scientific work of the Frequency Combs project is one of the top five comb efforts, but at present it is not completely clear what applications the frequency comb is good for other than NIST-specific goals for timekeeping and time and frequency transfer. Specifically, the EEEL is pursuing its own program with these combs separate from the timekeeping group, and there is possibly a huge potential for the combs outside of frequency standards that needs to be pursued. The use of the combs in telecommunications-component characterization was very good, but other applications to communications, other than the long-distance time transfer, were not apparent. For example, in satellite communications there is a need for extremely accurate time synchronization. The frequency-comb time-transfer experiment between clocks in the Boulder, Colorado, area was spectacular but now seems completed. The group could explore whether these techniques can be useful over longer distances or from Earth to space platforms. Another potential application is in systems such as light detection and ranging (LIDAR) remote sensing. The laboratory equipment seemed adequate, given that the fiber comb technology is less sensitive to environmental factors, such as temperature, than is some of the other interferometric work. A challenge now is to find in the EEEL the nonfrequency transfer and timekeeping applications of the combs, of which there are likely many. More outreach and discussion between NIST scientists and other agencies are needed to flesh out all of the applications. Terahertz Technology Project One goal of the Terahertz Technology project is to develop methods for calibrating optical power in the millimeter-wave to terahertz frequency range. The EEEL has served industry by acting as an unbiased tester for participants in a program of the Defense Advanced Research Projects Agency (DARPA) and has demonstrated new methods such as the blackbody calibration source for terahertz measurements. Other projects include the demonstration of a video-rate passive imaging. The results are among the best for uncooled niobium micro-bolometers used in concealed weapons detection. Funding sources for this project include the Department of Homeland Security. It is unclear whether there is there a plan to transfer this technology to industry. Overall, the project seems to be meeting the goal of real-time video systems. This effort represents a good example of the leadership that NIST can provide to new industries. The project is also achieving the goal of supporting industry. Quantum Information and Terahertz Technology Project The most striking work in the Quantum Information and Terahertz Technology project group is the development and deployment of the transition-edge superconducting (TES) photon-number-resolving detectors. This unique work is in demand worldwide, as high-efficiency detectors with number-resolving capability are viewed as a critical 11
element in optical quantum information processing, quantum imaging, and quantum sensing. The TES detectors are currently the most efficient photon counters at any wavelength, but in particular, in the important telecommunications band. In order to be relevant for some applications (e.g., optical quantum computing), however, the time response still requires further improvements. The superconducting single-photon detector (SSPD) work is also excellent, and the high-speed response has been critical for applications, such as large-bandwidth quantum communications; however, the SSPD efficiency (approximately 0.5 percent now) needs further improvement, but there is steady work in this direction. The generation of approximate Schrödinger cat states (by photon subtraction) is an interesting application of the photon-number-resolving characteristics of the high- efficiency TES detectors. Although it may be hard to justify this sort of fundamental project on a mission basis, it is an example of the unique fundamental research that NIST can do, because of a combination of a very good source of squeezed light combined with a TES detector that nobody else has. The correlated-photon work using four-wave mixing seems to be progressing very well, with very high coincidence to accidental rates, a necessary prerequisite to generating efficient heralded photons and high-fidelity entanglement. The projectâs researchers all demonstrate commitment and dedication. However, inadequate infrastructure was clearly observed by the panel. For instance, some of the work requires stable interferometers that are extremely difficult to maintain in the current laboratories, with the radical temperature swings and a poor heating, ventilating, and air- conditioning (HVAC) system. The laboratory spaces in general are severely cramped, and the temperature control was almost completely lacking in some areas. The laboratories that require stable optical alignment associated with single-photon production, characterization, and detection probably should be relocated in the new building that is being constructed on the NIST campus in Boulder, Colorado. The planned renovations of existing space may mitigate this concern. There is a growing need to be able to transition the TES detectors into other research laboratories around the country. The demand for the TES detectors may grow considerably in the next few years. More funding will be needed, not only to produce the detectors (and associated support systems) at a more rapid rate, but also for the training of support personnel, who can assist with the transport, installation, and maintenance of the detectors in government, university, and industrial laboratories. The efforts of this group have helped to push the worldwide effort toward faster and more efficient detectors for quantum information applicationsâfor example, quantum cryptography, especially in collaboration with other, external groups. These detectors have enabled some of the best results in this area. Increasing the speed of the TES detectors and increasing the efficiency of the SSPDs are obviously major goals, as is improving the system robustness to facilitate the adoption of the technology by outside entities. The detectors based on semiconductor quantum dots could eventually have a large impact (given the need to have fully integrated systems), though at present the low net efficiencies preclude this. 12
Linear Optical Waveform Metrology Project In the Linear Optical Waveform Metrology project, linear optical methods for the full-vector (amplitude, phase, and polarization) characterization of repetitive optical signals have been developed. The state of the art of pulse measurement is usually nonlinear optical methods, such as frequency-resolved optical gating. Nonlinear optical methods can be limited in their utility by weak optical signals or an inability to achieve high resolution over long time periods. Competing linear optical methods include spectral interferometry, which can perform a similar analysis. However, there is a real niche for a full-vector characterization platform that employs single-element detection (performed in the time domain) as developed by NIST especially as work continues on arbitrary waveform generation. The laboratory space suffers from the same problems that other laboratory spaces are experiencing, specifically, lack of sufficient HVAC capacity. The staffing resources seem to be sufficient. This calibration capability is a significant technical achievement that will be of service to the optoelectronics industry. Nanostructure Characterization Project The gallium nitride (GaN) nanowire growth effort in the Nanostructure Characterization project is making superb defect-free material, potentially providing breakthroughs for unique devices; the quality is particularly impressive given the comparatively limited investment in this project. The development of other novel single- photon detection techniquesâfor example, using semiconductor quantum dots to realize an optically gated field-effect transistorâshould also be pursued as a means of realizing high-efficiency photon-number-resolving detectors; this is particularly true given the push toward fully integrated systems. The molecular beam epitaxy (MBE) facility dedicated to gallium nitride growth is âhome-built,â and the facility is quite cramped. An improved facility would increase the rate of progress on this effort. While the nanowire material is unique in terms of its perfection, the measurements characterizing the material are fairly standard. The proposed goal of creating a quantum wire ultraviolet laser as a source for quantum computing is a good fit to the goals of the Optoelectronics Division. In order to be successful, the effort needs stronger collaboration, guidance, and support from device designers. SEMICONDUCTOR ELECTRONICS DIVISION Overall, the quality of the technical work of the Semiconductor Electronics Division is very good, being nationally competitive and with some areas being among the best in the field. The division appears to be positioning itself well to play a significant role in the emerging priorities, such as the Smart Grid and bioelectronics, and it provides a leadership role on many of the electronics measurement and standards committees. There continues to be significant infrastructure renovation within the division. A 13
proposed center for nanoelectronics reliability is an important focus that takes advantage of expertise residing in the division. MicroNano Technology Project The focus of the MicroNano Technology project is âmore than Mooreâ: that is, increasing integration of functions in combination with the size reduction of components producing the positive effect of stimulating the enhancement rates for both system miniaturization and system complexity. These effects are strongly in play at the present time, stimulated by developments in areas such as wireless systems, bioelectronics, distributed-sensor arrays, and micro-robotics, among others. NIST has a role to play in defining standards and in stimulating the U.S. efforts for this area. The continuing reduction in component sizes poses challenges in the understanding of materials, as well as in the behavior of structures and electronic devices. The listing of project-related internal proposals, press releases, reports, peer-reviewed technical papers, and the participation of project staff in professional activities was impressive, reflecting the teamâs diverse achievements. However, more attention should be devoted to reporting research publications. The budget and staffing for this area both appear to be adequate. Some of the important work of the MicroNano Technology project includes the development of three ASTM International and three SEMI (Semiconductor Equipment and Materials International) microelectromechanical systems (MEMS) standards (five for MEMS structures and one for wafer bonding); the wafer-bonding work involves extensive collaborations in the United States and European Union and collaborative associations to define values and measurement standards for the Youngâs modulus in materials used for MEMS structures. Micro-/nano-fluidic metrology provided three new measurement tools for nanoparticles. These include the microfluidic formation of liposomes to enable the electronic control of particle size and the composition of encapsulated species, with ongoing work to extend the capability to control charge and species. Researchers have demonstrated microwave heating in microfluidics to generate steep temperature gradients that enable temperature-gradient focusing. This appears to be a pioneering effort that can open new application avenues. The bioMEMS area to monitor cell growth using electronic monitoring is being investigated at an increasing number of laboratories around the world as more and more researchers become aware of the unfolding promise when nanotechnologies are applied to problems and opportunities in bioelectronics. As technologies advance for the production of structures with nanometer dimensional resolution, commercial progress is strongly in need of new standards and characterization procedures. The project team is responding appropriately to meet these needs. 14
Macro Electronics Project Organic electronics is a new thrust in the industry. There were 10 publications from the Macro Electronics project between 2006 and 2008, several in journals such as Nature Materials, Applied Physics Letters, and Chemistry of Materials. The principal investigator for this project is well recognized in the area of organic/flexible electronics, having more than 40 peer-reviewed publications and more than 3,400 citations to his creditâan impressive record. The project, undertaken by 1 full-time equivalent in staff and 1.5 associates, is barely at critical mass. With the activity expanding into organic photovoltaics and displays, the project will be severely strained without additional staffing. The effort in understanding of device characterization and device reliability has just begun for organic electronics and flexible electronics. The team can provide a leadership role in developing the proper procedures for characterizing organic thin-film transistors and PVs. Because the degradation mechanisms are not well understood, there are no defined procedures for accelerated life testing. These methodologies need to be developed in order for organic electronics to become pervasive. Macroelectronics is as important as nanoelectronics and microelectronics. This project is severely underfunded. Infrastructure for Integrated Electronic Design and Manufacturing Project While the project on Infrastructure for Integrated Electronic Design and Manufacturing (IIEDM) continues to do good work, there is little interaction between the divisionâs core technology groups and the IIEDM group. Approximately 80 percent of the funding for the group comes from NIST non-base funding. The group appears to have adequate space and infrastructure to carry out its work. Knowledge Facilitation Project The Knowledge Facilitation project provides computer programming expertise for NIST. The project constitutes primarily a service organization providing information technology (IT) project support to the rest of NIST. The group does a good job of developing NIST-specific IT tools and is not involved in developing measurement standards. It has developed an active radio-frequency identification (RFID) inventory tracking system for tracking capital assets within NIST. The group also developed a trip- report tracking system. Nanobiotechnology Project The metrology involved in the Nanobiotechnology project is enabled by the use of biological nanopores, using high-input impedance electrical measurement tools to characterize the direct current (dc) and alternating current (ac) electrical and gating properties of single biological molecules. The three key activities within the project are bioelectronics for systems biology, bioelectrical optical measurements related to anthrax detection, and the structural biology of membrane proteins. These activities have 15
garnered significant national and international recognition arising from the project membersâ high-impact publications and multiple national and international invited talks. The Nanobiotechnology project team has been highly productive in applying high-performance electrical tools, leading in the demonstration of the detection and measurement of the electrical properties of single molecules and in providing insight into the mechanistic performance of biological nanopores. These efforts are addressing a critical need in the qualified metrology of single molecules and of biological nanopores. The system for single-molecule detection of spontaneously assembled and immobilized biological nanopores on solid surfaces has the potential to emerge as a high-throughput detection platform when combined with a suitable solid-state transduction modality. If realized, this activity will contribute to the development of a novel technology platform that becomes enabling for functional proteomics, and these broad capabilities at the intersection of silicon and biology could be leveraged toward analyses of other macromolecules for a variety of applications, such as drug screening and the analyses of neuromorphic systems. This project has the potential to serve as a cornerstone for a new bioelectronics thrust; it can greatly benefit from an integrated in silico component and from strengthened collaborations with established protein molecular modelers. Given the available human, budgetary, and facilities resources, the output of this project is impressive. However, the small group appears to be engaged in far too many different activities, given the available resources. The group will need to add capabilities in areas such as theoretical modeling and simulation, through either collaborations or internal new hiring. The Nanobiotechnology project is focused on developing technologies that will permit the accurate and simultaneous measurement of many macrobiomolecules. This area has major unknowns, and fundamental understanding and breakthroughs are needed across multiple disciplinary boundaries. The three key activities mentioned above are being used as models to help push forward the basic understanding in the field. Power Devices and Thermal Metrology Project The emphasis for the Power Devices and Thermal Metrology project is to develop electrical and thermal management methods and equipment in support of the development of advanced power semiconductor devices and integrated circuits (ICs). This project has the opportunity to make use of its expertise in device reliability and power device system integration to help improve the fundamental understanding of device aging, degradation, and failure mechanisms. The power device group will be a focal point for the Smart Grid work. The team is an established leader in silicon carbide (SiC) power device insertion into power system switching applications and is currently the leader in high-voltage/high- power measurement techniques. Its principal investigator is recognized as one of the leaders in the field of high-voltage device characterization and the integration of high- voltage devices into power systems. The Department of Defense and Department of Energy rely heavily on this team to characterize high-power devices for many of their applications. 16
The current infrastructure and budget for the Power Device and Thermal Metrology group seem to be adequate. The team has developed a unique set of capabilities for making high-voltage and high-temperature measurements and is recognized as the national leader in making these measurements. This expertise will be critical in implementing Smart Grid technologies, where high-voltage switches and solid-state power converters will be required. As it expands into Smart Grid activities, this project should be a focal point for the division. Nanoelectronic Device Metrology Project The Nanoelectronic Device Metrology project seeks to create test structures and associated measurement methodologies for specific target technologies: electronics based on semiconductor nanowires and confined-Si (the logical extension of silicon complementary metal-oxide-semiconductor, Si-CMOS); molecular electronics; organic spintronics; memristors; and selected carbon-based electronics. Its activities are divided into four areas of concentration: 40 percent addresses target molecular electronic structures and technologies, 50 percent is divided equally between silicon and nonsilicon nanoelectronic devices and technologies, and 10 percent is devoted to capacitance metrology at ultimate scales. The team is providing standards for capacitance measurements in the attofarad (10-18 F) range and is pursuing a number of issues in the molecular electronics area. Obtaining reliable interfaces to measurement structures for molecular-electronic assemblies is particularly challenging. Another research area centers on interfaces of CMOS with molecular structures in order to enable new configurable characterization methods. An important achievement in this work has been a capability to produce ultrasmooth goldâspecifically, large areas on a flexible substrate. The gold is five times smoother than any surfaces reported thus far. Office of Microelectronics Programs support for the project has consistently been strong, ranging from 62 percent of the total budget projected in fiscal year (FY) 2009 to 71 percent in FY 2008, 63 percent in FY 2007, and 77 percent in FY 2006. The team has demonstrated strong productivity, being responsible for 30 papers and 52 talks (15 invited) since FY 2007. Members are also active in leadership roles in professional activities. However, two important research capabilities should be established in support of this work: a direct link to modeling and simulation studies and a closer tie to experts with a focus on the properties of materials. The significance of modeling and simulation to the success of the silicon IC technologies is unquestioned. Especially for the research involving CMOS interfaces with molecular structures, there is need either for in-house modeling and simulation or for strong bridging to places where these skills exist. Materials and their characterization are central to the full gamut of research, and it is important that researchers with a strong understanding in these areas be involved. The possible links to basic materials research areas in NIST should be explored. 17
Advanced Metal-Oxide-Semiconductor (MOS) Device Reliability and Characterization Project With the CMOS technology scaled to below 50 nm dimensions at integration levels of 109 transistors per chip, device reliability is becoming an ever more critical issue in very large scale integration (VLSI) product assurance. A single defect developed during the use period could cause chip and system failure. The role played by the project team is vital to the microelectronics industry and national interest. With the teamâs recognized leadership position in metal-oxide-semiconductor field-effect transistor (MOSFET) device reliability characterization, its recent accomplishments extend to the following: understanding of the physical mechanism of negative-temperature bias instabilityâone of the most serious reliability issues in advanced CMOS technology; the study of defect generation in a high-k dielectric stack under electrical stress; the development of an ultrasensitive capacitance probe for measuring a nanometer transistor directly; the application of microelectron paramagnetic resonance spectrometer for measuring a single defect; the characterization of new materials by scanning capacitance microscopy and scanning Kelvin probe microscopy; and the optical-electrical characterization of a high-k gate dielectric on III-V compound semiconductors. The team has also extended its expertise in the characterization of semiconductor-insulator interfaces to other material systems needed by the microelectronics industry or by national defense, including high-k/silicon dioxide (SiO2) on SiC MOSFETs, high-k dielectric on III-V compound semiconductors, zinc oxide (ZnO) nanowire MOSFETs, and time-dependent dielectric breakdown of SiO2/SiC devices. Its technical accomplishments have enabled this group to interact extensively with the microelectronics industry and other agencies, allowing it to respond to industry priorities and to meet their needs. The impact of this team on the science and technology (S&T) of MOS reliability is evidenced by the high-quality papers that this group has published and the invited talks presented at major international workshops and conferences. A weakness of the project is the lack of extensive simulation efforts for more in-depth understanding and modeling of the characterization results. QUANTUM ELECTRICAL METROLOGY DIVISION The Quantum Electrical Metrology (QEM) Division, located in the Boulder, Colorado, and Gaithersburg, Maryland, NIST facilities, executes an impressive, well- coordinated, and highly synergistic effort in applied and fundamental, leading-edge research and is well matched to the mission of NIST and, in particular, to that of the EEEL. The three groups in this division, which are the Quantum Devices group in Boulder and the Gaithersburg groups in Fundamental Electrical Measurements and Applied Electrical Metrology, provide the following technologies and services: quantum- based standards in the area of dc and ac voltage, power, and resistance; quantum sensors with ultrahigh energy resolution; quantum information devices for the realization of quantum networks, as well as quantum measurements; advanced materials research that 18
enables the sustained improvement of these devices; a classical standard for capacitance; a realization of the electronic kilogram; and increasing activities toward smart energy grid technology and related measurement devices and protocols, such as the synchro- phasor and power measurement units and cryogenic current comparators (CCC) to provide a direct link to quantized Hall resistance (QHR) over nine orders of magnitude. The efficiency and effectiveness of the division are maximized through the phaseout of programs that are not productive, that are missing synergy, or that are not important to the mission. There is collaboration with other agencies, industry, and academia, and common S&T goals are pursued; for example, high-resolution gamma-ray and alpha-particle detectors are delivered to the Los Alamos National Laboratory. Despite continued flat funding over years, the Quantum Electrical Metrology Division has been able to acquire increasing outside funding and to excel in new areas, such as quantum information. Though the division has not received new funding for work on smart grid technologies, it is shifting resources to start this new, important program area. A key asset of the division is its unique Quantum Device Fabrication Facility, which is well managed and will be enhanced substantially by the new construction under way in Boulder. The equipment at both locations is excellent and state of the art. However, due to the continued decline of scientific and technical research services (STRS) funding and the fact that the number of permanent staff is at an all-time low, further reductions in staff may threaten core programs of the division. The cohesive and synergistic group organization has so far been able to cope with the reduced internal funding and is continuing to provide stability to the division. The Boulder group has achieved an effective level of integration, not just in technical tools but also in the innovation of aligned and cooperative advances. One example is the Josephson voltage standard (JVS) work, which ranges from Josephson array fabrication to the development of a fully automated measurement tool for metrological evaluation and application that enables the dissemination of this standard to Gaithersburg and around the world. The complexity of this system needs a sustained engineering effort to maximize its impact. Quantum Voltage Project As one of the leaders in the use of Josephson voltage standards for purposes of electrical metrology, the Quantum Voltage project is now close to demonstrating a 10 V programmable standard that would significantly simplify many calibration procedures worldwide by allowing more direct comparisons. The project team is also the leader in generating state-of-the-art waveforms with amplitudes of 275 mV at up to a few hundred kilohertz. The goal is to extend these results to amplitudes up to 1 V with frequencies up to 1 MHz. Ultimately, the hope is to replace existing standards such as thermal converters. An exciting application of this arbitrary waveform synthesis is related to measurements of the Boltzmann constant by using a quantized voltage noise source to calibrate the Johnson noise of a resistor at a known temperature. The result will be the first electrical measurement of the Boltzmann constant. The expected uncertainty (on the order of 6 ppm) would be competitive with other measurements. 19
Support for this project, unlike many at the Boulder site, is currently based entirely on internal NIST funding. For many years this was not the case, but changes in the funding climate caused a shift away from outside-agency funding. This change has created pressure on the Quantum Voltage project leader to consider a greater focus on more applied programs that could bring in external support. The Quantum Voltage project has an enormous impact. Its efforts often drive the direction followed elsewhere. For example, recently the team convinced others in the field that the usual dc Josephson voltages standards, while appropriate for dc and 60 Hz applications, will not work as a standard for higher frequencies. The result has been significant work worldwide over the past 2 years in ac quantum standards. International partnerships are formed to foster the advancement of scientific frontiers and accelerate the progress of science across borders through the exchange for standards, for example the JVS, and formal collaborations with other national metrology institutes (NMIs; in China and Mexico). Quantum Sensors Project The Quantum Sensors project team continues to produce leading sensors, primarily based on superconducting quantum interference devices (SQUIDs), including spectrometers for x-ray, gamma/alpha, and microwave background polarimetry. Many of these have spectral resolution several times better than that of the closest classical technology. Recent work has included the development of multiplexed SQUID arrays for the International X-ray Observatory. Continued work on transition-edge sensors has allowed a new understanding of excess noise issues, which should allow continued device optimization. The project is also leading an effort in nuclear forensics. The use of high-resolution gamma-ray spectroscopy, driven by a leading gamma energy resolution of 22 eV at 100 keV, may allow the nondestructive assay of spent reactor fuel. This project has recently enjoyed a very high level of outside-agency support. Sensors produced by this project have been delivered to multiple users in government and academia, including the Los Alamos National Laboratory and multiple telescopes around the world. The project has very high impact. Quantum Information and Measurements Project Efforts in the Quantum Information and Measurements project are competitive with other major groups worldwide, as evidenced by recent publications in leading journals such as Nature. The team is involved with the development of air-gap capacitors for improved qubit performance. The elimination of an oxide dielectric has given some improvement in coherence times. Efforts are ongoing to couple multiple qubits together through a superconducting bus in an attempt to create prototype quantum processors. A large portion of the support for this project is derived from competitive internal NIST funding. The work, particularly with regard to the coupling of qubits through a superconducting bus, is having significant impact on its field, as indicated by high-profile publications. 20
Quantum Materials Project Developing epitaxial dielectrics for use in Josephson-junction-based qubits is the main task of the Quantum Materials project. The project members were the first to use such techniques to produce and characterize qubits based on epitaxial Josephson junctions, and they demonstrated that such growth techniques can significantly increase decoherence times. Support for the project is good; it includes some outside-agency funding. There is potential for extremely high impact in the quantum information science community once the results associated with epitaxial growth are more widely disseminated. Quantum Fabrication Facility Project The Quantum Fabrication Facility project maintains the Boulder clean room and its extraordinary capability for the fabrication of integrated Josephson-junction circuits. The pressure on the Boulder fabrication facility will be reduced by the new fabrication facility under construction and enabled by stimulus funds from the American Recovery and Reinvestment Act of 2009. However, the existing clean-room management model (i.e., the facility is run by the QEM group in Boulder but used by many other Boulder groups) cannot be extended to the new enlarged facility. A new approach toward fabrication facility management is being developed to maintain this unique fabrication facility while expanding its throughput. Particular support for this project includes the new clean room and associated fabrication equipment that will be created in the new building on the Boulder campus. This project enables many of the other activities at the Boulder campus. Its impact is, therefore, best measured through that of the other projects, which, as discussed above, is extremely high. Metrology of the Ohm Project The Metrology of the Ohm effort provides an excellent calibration service that is a significant and stable source of income and serves a broad array of industrial and government customers. The project team has made efforts to expand its work into new areas. These include the development of a new, easier-to-operate cryogenic current comparator that will, it is hoped, be commercialized and made generally available. New efforts also include collaboration with the new Quantum Conductance project, which involves the development of graphene-based quantum Hall devices, as well as the development of expertise in bioelectronics. The Metrology of the OHM project is supported in part by a stable, well-regarded calibration service that is highly valued by industry. The project has led comparisons of resistance measurements at multiple scales and has delivered the new CCCs to three other national metrology institutes, in Argentina, Australia, and Mexico. 21
AC-DC2 Project The AC-DC2 project combines the earlier AC/DC and DC projects for simplified management. A significant amount of effort is given to very high quality calibration services for both ac and dc measurements. Research is focusing on the development of new thermal voltage converters, based on multijunction technology that should allow operation at frequencies up to 100 MHz and voltages of 2 V. This will cover a range of frequencies, voltages, and currents that cannot be reached by the ac Josephson voltage source (ACJVS). Project staff is also working with the Quantum Voltage project team in Boulder in the development of a 10 V programmable Josephson voltage standard (PJVS). Calibration services, while excellent, are currently at risk, especially dc voltage calibrations. The service provided for standard calibration is not properly charged, leading to low revenue for NIST. The project has begun the dissemination of ac voltage standards based on ACJVSs, allowing state-of-the-art accuracy in comparison of ac and dc voltages to become more widely available. Electronic Kilogram Project The artifact mass standard for the kilogram unit is suffering from 120 years of wear and contamination, so its value over time is becoming uncertain at several parts in 108. As a potential replacement, the Electronic Kilogram project compares the energy in power generated by mechanical and electrical means. Einsteinâs famous equation E = mc2 can relate this energy measurement to mass. Except for the kilogram, the standard units involved are all quantum-based: the second (atomic clocks), meter (laser wavelength), volt (Josephson effect), and ohm (quantum Hall effect). These are all unchanging in time. The result is a measured value for the Planck constant, h, relative to the mass artifact standard, or vice versa, if the international community redefines mass in terms of a value for h. Stable results have been produced by the Electronic Kilogram project for the past 4 years, and the project is aiming to produce improved results by the end of 2010 in considering the redefinition of the kilogram. The project has attained the best relative uncertainty, and work is in progress to improve the uncertainty to 20 ppb. Efforts to design a new electronic kilogram calibration system for use after a potential redefinition are also underway. Support for this project, despite its fundamental significance, has been minimal over the past few years, with staffing dropping from four or five people to only one at present. To the present time, this project has produced the most accurate measurement of Planckâs constant. The project also plays a leading role in the upcoming redefinition of the International System (SI) of units. Quantum Conductance Project The goal of the Quantum Conductance project is to develop graphene-based quantum Hall effect devices that will do for resistance metrology what the development of the Josephson voltage source did for voltage metrology. These graphene-based devices should be able to operate at higher temperatures than gallium arsenide (GaAs)-based 22
quantum Hall devices, and they could possibly be easier to produce. An informal graphene group, involving NIST staff at both Gaithersburg and Boulder, has been formed, and collaboration with the Resistance Metrology project is also underway. The support for the Quantum Conductance project is reasonable, although at the moment the project has only one staff member. The project is new, and its impact has yet to be determined. The potential impact could be very high if an easily disseminated quantum resistance standard can be developed. Farad and Impedance Metrology Project A significant new effortâthe Farad and Impedance Metrology projectâis underway, focusing on the development of a new capacitance metrology project. This project would make use of frequency combs for length measurement and will, it is hoped, result in a 10-fold improvement in calibration accuracy. It may allow calibration to be extended to the femtofarad regime, which is important for efforts in nanoscale science. It is hoped that the new standard will be more portable and automated than the existing calculable capacitor; the new standard has a target accuracy of 5 ppb. This project is the leader in the field of uncertainties for capacitance measurements. The project staff recently organized and led a multination capacitance comparison for several countries in the Americas. Capacitance calibrations, driven by customer needs, have generated income of $200,000 in FY 2008, which is commendable. Electric Power Metrology Project The Electric Power Metrology project has now moved to a quantum standard, based on stepwise sine wave approximation using a Josephson voltage source. As a result, uncertainties have been reduced by a factor of five. The other major effort of this project has been focused on the synchro-phasor effort, and on the development of techniques for the measurement of dynamical waveforms. Synchro-phasors have become increasingly important to power system operators, and the synchro-phasor test laboratory developed at NIST provides a state-of-the-art testing tool for phasor measurement units (PMUs), to verify that they meet the current industry standard and to provide an assurance of the interoperability of PMUs of different manufacture. Support for this project seems reasonable. The work of this project has significant impact on industry, and the project staff is also closely involved with the new Smart Grid effort. Smart Grid Interoperability Standards Development Project Unlike the other projects of the Quantum Electrical Metrology Division, the Smart Grid Interoperability Standards Development project is not technical in nature, but instead leverages NISTâs position as a neutral and objective source of technical information to play a role in developing a new set of standards and performance testing. This fast-moving project represents both a significant opportunity and a risk for the division. The effort has greatly raised NISTâs visibility in this area and is expected eventually to lead to new research programs. Although this project is too new for its 23
impact to be accurately judged, it is nonetheless the focus of intense interest and has the potential for extremely high impact. ELECTROMAGNETICS DIVISION The Electromagnetics Division consists of top-quality researchers who serve in several journal editorial positions and on standards bodies. Much progress in the projects of this division was noted by the panel. However, project prioritization and budgets remain sketchy. Strategic projects were not well defined, in part due to the uncertainty associated with the leadership and budgets. There might be too many projects for the number of full-time staff in the division. While some calibration/standards functions are curtailed and mothballed at end of life, there needs to be a means of capturing the years of learning associated with these efforts. One way is to put together handbooks on the standards calibration and methodology that would otherwise be lost. One example of this is the book Experimental Techniques for Low Temperature Measurements, published by Oxford University Press in 2006 (ISBN-13: 9780198570547; see the subsection below). Superconductivity Program The Superconductivity program team has a reputation for being the best for its sustained work in characterizing the behavior of superconductors. This team has been uniquely influential in setting worldwide standards for making such measurements and in improving the basic understanding of the impact of mechanical strain on behavior. Team collaborations with other U.S. government agencies, U.S. industry, and institutions and projects throughout the world are commendable. It is noted that the continuity in the specialized skills is maintained by overlap between the long-term members and the young members of the team. The volume Experimental Techniques for Low Temperature Measurements referenced above, written by a recently retired staff member, presents a model for outreach and transfer of information. The concept of fully documenting specialized knowledge before retirement should be facilitated. The concept of writing teams can be useful in this regard. Biomagnetics Program New metrology work being done by the Biomagnetics program to support magnetic resonance imaging (MRI) devices has high technical merit. The necessary close collaboration with the medical community is evident. The initiative by the team to develop a smart contrast medium for use with MRI devices also has widespread potential. The decision by the EEEL to purchase a nuclear magnetic resonance (NMR) system, needed for biomagnetics as a dedicated MRI machine, free from clinical scheduling, is strongly supported. However, it will be a requirement that such a facility also have a close collaboration with one or more medical radiologists. The development of spectroscopic detection at terahertz frequency for molecule identification (for purposes 24
of biology and homeland security) and of microsystems for quantitative metrology of scanning probe microscopes (magnetic nanoparticle manipulation) are two new activities considered incubator initiatives. Nanomagnetics Program Initiatives of the Nanomagnetics program in spintronics and in dense-pack recording medium and switching are in sync with rapid and widespread growing interest in the broader community. The underlying goal of the work is to develop the metrology for studying these nanodevices, but in pursuing that goal it is necessary to be intimately familiar with the development and improvement of those devices. The necessary depth of understanding for device development is evident in the work presented. Nevertheless, the staff must be vigilant to undertake work that is generic and focused on widely useful metrology and not on device development for its own sake. Field Parameters and Electromagnetic Compatibility (EMC) Applications Project The Field Parameters and Electromagnetic Compatibility (EMC) Applications project is advancing the state of the art in measurements for transverse electromagnetic (EM) cells, reverberation chambers, calibration field probes, and open-air test sites. It also provides measurements in an anechoic chamber. The resources for the project are adequate. This project is important for the metrology mission of the division. Wireless Systems Project The wireless industry has welcomed the development, standardization, and popularization of reverberation chambers for EMC use, as the chambers enable easy, compact, and inexpensive measurements. The reverberation chamber provides a repeatable multipath simulation environment for wireless device testing. However, NIST has the responsibility to inform its wireless customers that conventional measurements of pattern and polarization are critical in the design and development of new systems and hardware. Reverberation chambers alone are insufficient. The project completed an interesting study of the electromagnetic environment in buildings that are being destroyed. The facilities for this project are adequate. The project is in keeping with the metrology and standards missions of NIST and has been specifically sought by wireless providers. Antenna Metrology Project The work in the Antenna Metrology project on the development of near-field scanning metrology for antennas is outstanding. NIST led the development of near-field scanning many years ago and has, in the intervening years, significantly refined the technique for gain and pattern measurements, especially for very short wavelengths. The resources for the project are adequate. 25
Fundamental Guided Wave Metrology Project The enhanced effort of the Fundamental Guided Wave Metrology project on the waveform for over 200 GHz is timely, as the operating frequencies have continued to rise. The measurement of noise other than thermal noise should also be looked at, and the swift development of four and multiport s parameters and Automatic Network Analyzer (ANA) measurement calibration is essential because more and more differential circuits are penetrating into radio-frequency (RF) front ends. There is need for updating of equipment to handle new connector types and higher frequencies and for extending metrology to waveforms of greater complexity and bandwidth. The Electromagnetics Divisionâs stated objective for measurement services is to evolve services for greater efficiency and better support for customers. This objective is being met. With respect to the objective of developing better on-wafer noise and s- parameter techniques, the work is in early stages, with appropriate direction. For the objective of redeveloping primary power standards (to find substitutes for nonreplaceable primary transfer standards), the work is in early stages, with appropriate direction. With respect to the objective of developing fast pulse sources for waveform measurements up to 400 GHz, at present up to 200 GHz has been worked out, and work is in progress for 200 to 400 GHz. Advanced High-Frequency Devices Project For the Advanced High-Frequency Devices projectâs objective of developing techniques for determining EM device characteristics of nanoscale devices (spin currents, resistivity, etc.), an understanding of electrical characteristics and nanoscale devices, such as nanowires and nanotubes, is critically important and encouraged for the beyond- CMOS era. The results eventually contribute to industrial device development. For the projectâs objective of expanding network analysis to beyond the 50 ohm world, at present most high-frequency measurement is carried out in the 50 ohm environment; however, non-50 ohm characterization is increasingly relevant for such environments as nanowire electronics. The establishment of more streamlined procedures is encouraged. The scope of the work of this project appears to be aligned with its resources. No significant lack of instrumentation appears to exist. Advanced Materials Metrology Project Five tasks of the Advanced Materials Metrology project were briefed to the panel during the review. The basic thrust of these tasks is to support the electronics industry through classical measurements of substrates and printed-circuit-board materials and to apply this knowledge to such areas as homeland security and bioscience. An understanding of the basic interaction between EM waves and molecular structure is essential. The challenge is to extend this understanding to terahertz frequencies and nanometer scale. What the EEEL brings to this effort, in contrast to university and commercial laboratories, is the ability to identify and describe best 26
practices and a respect for uncertainties in measurement. The project has been characterizing the permittivity and permeability of various materials. It has developed on- wafer probing for substrate and thin films, in particular, low-k materials for microelectronics applications. The method based on a split-cylinder resonator for material characterization has been developed within NIST, together with some international collaboration. This technique has been transitioned to industry successfully. In many measurement schemes, there is a difference between measurement uncertainty and device physics uncertainty. Such information is desirable. Recent work on the evanescent probe method provides a new dimension of noninvasive and nondestructive measurement capabilities. The biochemistry project is in line with national priorities. Because of the limited resources, it is necessary to concentrate on the unique mission of supporting basic physics with metrology, analysis of uncertainties, and reduction of errors through an understanding of instrumental and basic physical limitations. The stated objectives of the project are broad and generally amount to maintaining and expanding NISTâs ability to support industry and other government agencies. The project team appears to be making adequate progress toward these goals. 27
