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OCR for page R1
Materials for High-Temperature
Semiconductor Devices
Committee on
Materials for High-Temperature
Semiconductor Devices
National Materials Advisory Board
Commission on Engineering and Technical Systems
National Research Council
NMAB-474
National Academy Press
Washington, D.C. 1995
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NOTICE: The project that is the subject of this report was approved by the Governing Board of the National
Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National
Academy of Engineering, and the Institute of Medicine. The members of the committee responsible for the report
were chosen for their special competencies and with regard for appropriate balance.
This report has been reviewed by a group other than the authors according to procedures approved by a Report
Review Committee consisting of members of the National Academy of Sciences, the National Academy of
Engineering, and the Institute of Medicine.
This study by the National Materials Advisory Board was conducted under ARPA Order No. 8475 issued by
DARPA/CMO under Contract No. MDA 972-92-C-0028 with the U.S. Department of Defense and the National
Aeronautics and Space Administration.
The views and conclusions contained in this document are those of the authors and should not be interpreted
as representing the official policies, either expressed or implied, of the Defense Advanced Research Projects Agency
or the U.S. Government.
Library of Congress Catalog Card Number 95-70760
International Standard Book Number 0-309-05335-8
Available in limited supply from:
National Materials Advisory Board
2101 Constitution Avenue, NW
Washington, D.C. 20418
202-334-3505
nmab~nas.edu
Additional copies are available for sale from:
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Copyright 1995 by the National Academy of Sciences. All rights reserved.
Printed in the United States of America.
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Abstract
Major benefits to system architecture would result if cooling systems for components could be eliminated without
compromising performance (e.g., power, efficiency, and speed). The existence of commercially available high-
temperature semiconductor devices would be an enabling technology in such areas as sensors and controls for
aircraft, high-power switching devices for the electric power industry, and control electronics for the nuclear power
industry. This report surveys the state of the art for the three major wide bandgap materials for high-temperature
semiconductor devices (i.e., silicon carbide, the nitrides, and diamond); assesses the national and international
efforts to develop high-temperature semiconductors; identifies the technical barriers to their development and
manufacture; determines the criteria for successfully packaging and integrating new high-temperature semiconductors
into existing systems; recommends future research priorities; and suggests additional possible applications and
advantages.
· · ~
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The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished scholars
engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their
use for the general welfare. Upon the authority of the charter granted to it by the Congress in 1863, the Academy
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The Council is administered jointly by both Academies and the Institute of Medicine. Dr. Bruce Alberts and Dr.
Harold Liebowitz are chairman and vice chairman, respectively, of the National Research Council.
1V
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Committee on Materials for
High-Temperature Semiconductor Devices
WOLFGANG J. CHOYKE, Chair, Professor, Department of Physics, University of Pittsburgh, Pennsylvania
MICHAEL G. ADLERSTEIN, Consulting Scientist, Raytheon Research Division, Lexington, Massachusetts
JEROME J. CUOMO, Professor. Materials Science and Engineering, North Carolina State University, Raleigh
ARTHUR G. FOYT, Jr., Manager, Electronics Research, United Technologies Research Center, East Hartford,
Connecticut
EVELYN L. HU, Chair, Department of Electrical and Computer Engineering, University of California, Santa
Barbara
LIONEL C. KIMERLING, Professor, Materials Science and Engineering, Massachusetts Institute of Technology,
Cambridge
MARK R. PINTO, Department Head, ULSI, AT&T Bell Laboratories, Murray Hill, New Jersey
MICHAEL A. TAMOR, Staff Scientist, Ford Motor Company, Dearborn, Michigan
IWONA TURLIK, Vice-President, Corporate Manufacturing Research Center, Motorola, Schaumburg, Illinois
LIAISON REPRESENTATIVES
JANE A. ALEXANDER, ARPA/MTO, Arlington, Virginia
T.J. ALLARD, Sandia National Laboratories, Albuquerque, New Mexico
DON KING, Sandia National Laboratories, Albuquerque, New Mexico
WILLIAM C. M:ITCHEL, U.S. Air Force, Wright Patterson Air Force Base, Ohio
YOON SOO PARK, Office of Naval Research, Arlington, Virginia
J. ANTHONY POWELL, NASA Lewis Center, Cleveland, Ohio
JOHN PRATER, Army Research Office, Research Triangle Park, North Carolina
MAX YODER, Office of Naval Research, Arlington, Virginia
NMAB STAFF
ROBERT M. EHRENREICH, Senior Program Manager
PAT WILLIAMS, Senior Secretary
v
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National Materials Advisory Board
JAMES C. WILLIAMS, Chair, General Electric Company, Cincinnati, Ohio
JAN D. ACHENBACH, Northwestern University, Evanston, Illinois
BILL R. APPLETON, Oak Ridge National Laboratory, Oak Ridge, Tennessee
ROBERT R. BEEBE, Tucson, Arizona
I. MELVIN BERNSTEIN, Tufts University, Medford, Massachusetts
J. KEITH BRIMACOMBE, University of British Columbia, Vancouver, Canada
JOHN V. BUSCH, IBIS Associates, Inc., Wellesley, Massachusetts
HARRY E. COOK, University of Illinois, Urbana
ROBERT EAGAN, Sandia National Laboratories, Albuquerque, New Mexico
CAROLYN HANSSON, Queen's University, Kingston, Ontario, Canada
KRISTINA M. JOHNSON, University of Colorado, Boulder
LIONEL C. KIMERLING, Massachusetts Institute of Technology, Cambridge
JAMES E. MCGRATH, Virginia Polytechnic Institute and State University, Blacksburg
RICHARD S. MULLER, University of California, Berkeley
ELSA REICHMANIS, AT&T Bell Laboratories, Murray Hill, New Jersey
EDGAR A. STARKE, University of Virginia, Charlottesville
JOHN STRINGER, Electric Power Research Institute, Palo Alto, California
KATHLEEN C. TAYLOR, General Motors Corporation, Warren, Michigan
JAMES WAGNER, Johns Hopkins University, Baltimore, Maryland
JOSEPH WIRTH, Raychem Corporation, Menlo Park, California
ROBERT E. SCHAFRIK, Director
V1
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Preface
Just as human operators must be protected from
extreme environments, so must the electronics that
operate and control a functional system. When the
environment proves too warm, the electronics must
be insulated, refrigerated, or simply moved to cooler
locations. This last option is sometimes very difficult,
or impossible, and the perceived fragility of electron-
ics must then be reconsidered. Vacuum-tube technol-
ogy provides a historical example of this process.
Although vacuum tubes may be considered mechani-
cally fragile, tube-based radio proximity fuses were
nevertheless incorporated into artillery shells over 50
years ago! More recently, well-logging electronics
derived from available semiconductor technology
have been forced to operate for prolonged periods at
300 °C, far exceeding the "standard" limit of 125 °C
that appears on uncounted specification documents.
When the requirement is unavoidable and the motiva-
tion is high (e.g., commercial or military advantage),
"accepted" temperature limits need not be accepted.
There is a huge difference between what can be
done in principle and what should be undertaken in
practice, however. If the question were to be asked
"if a family of proven high-temperature electronics
functions (for the moment meaning anything higher
than 125 °C) were suddenly to become available,
would its ultimate economic value justify the cost of
its development," the answer is likely to be YES.
This position is further strengthened by the fact that
the shared virtues of radiation hardness, power han-
dling, aru] blue-light emission represent an important
leverage for the development of high-temperature
semiconductors. However, if the question were "is
· .
V11
there already a market for high-temperature electron-
ics sufficient to justify development of all or part of
the family function," the answer may not be so clear.
In all the processes of our economy, there are cur-
rently few in which insertion of electronics into such
environments is absolutely required to achieve accept-
able functionality. Recognizing that a human operator
can usually be protected and that a central controlling
computer is easier still to protect, the determination
of whether the benefits of high-temperature electron-
ics will justify the cost requires the examination of
how products and processes might be improved, or
even enabled, by high-temperature electronics.
The use of distributed control network architec-
tures and embedded processors is rapidly growing. In
a crude biological analogy, an animal is more agile,
efficient, and durable when its nervous system (sen-
sor signal processing), skeleton (physical structure),
and muscular system (actuator operation) are integrat-
ed. Electronics are integrated into systems for several
reasons: (1) to simplify control paths, thereby simpli-
fying wiring complexity, reducing weight, and im-
proving reliability; (2) to distribute control, allowing
robust system reliability and system architecture
simplification; (3) to permit operational information
to be gathered and processed with greater speed,
accuracy, and reliability; and (4) to control actuators.
For systems that encounter or generate high tempera-
tures, this integration, or entwining, demands that
electronics work at, or near, their functional tempera-
ture limit; the more intimate the integration, the
greater the environmental stress.
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Materials for High-Temperature Semiconductor Devices
If the economic value of extended-temperature
electronics justify its cost, a natural question arises:
"since the possibility of high-temperature electronics
has been known for decades and the need is so great,
why wasn't this done some time ago?" Although
there can be no definitive answer to this question,
there have been two historical barriers to the develop-
ment of high-temperature electronics.
First, the functions and performance goals of
most familiar complex electronic systems (e.g., tele-
communications and computers) are defined and
measured in purely electronic terms. Thus, although
it can be elaborate and expensive, the need for heat
protection is viewed as an unavoidable element of
system design, rather than of function.
Second, nonelectronic systems (e.g., turbine
engines, nuclear reactors, chemical refineries, and
metallurgical mills) are operable without embedded
electronic systems. Since the electronic function is
not the defining element of these systems and extend-
ed-temperature electronics are not available as a
robust off-the-shelf technology, many prospective
customers will not usually consider such systems.
Thus, although cognizant of the architectural advan-
tages of high-temperature electronics, prospective
developers have not perceived a general commercial
market sufficient to justify aggressive development.
Even with these barriers, however, considerable
international resources are currently being devoted to
developing electronic technologies either tailored for
or supportive of high-temperature operation. There is
a divergence in the central emphases of these efforts.
United States-Much of the focus is on
high-temperature electronics. One manufac-
turer markets a family of silicon-based
integrated circuits suitable for prolonged
operation at 250 °C, derived in part from
radiation-hardened technologies developed
for military applications. Silicon-carbide-
based devices are being developed for some
control applications and rudimentary dia-
mond-based devices have been demonstrat-
ed. Radiation-hardened electronics for reac
· · -
vail
tor control and waste monitoring are avidly
sought in both the United States and Europe.
The large bandgap and smaller neutron cross
sections of the lighter elements in high-
temperature semiconductors also translate to
radiation damage resistance. There are
approximately seven industry, three universi-
ty, and two national laboratory programs
currently active in the high-temperature
semiconductor field. The committee was
briefed by representatives of most of these
programs, which are listed on pages vi and
vii. There is also some funding of wide
bandgap semiconductors for use in high-
power devices (e.g., the Semiconductor
Research Corporation program at Purdue
University).
· Europ~Effort is mainly focused on power
electronics. This is synergistic with high
temperature because the generation of inter-
nal heat is a limiting factor in power devices
and is mitigated by larger bandgap and
higher thermal conductivity materials. A
collaborative organization, HITEN, was
formed in 1992 to coordinate European
nascent efforts in high-temperature electron
iCS.
Sweden Approximately 55 people are
engaged in research at Linkoping Uni-
versity and Kista in Stockholm. This is
a joint government-ABB industries effort
on power electronics, the first goal of
which is a 12 kV thyristor.
Germany The Deutsche Forschungs
Gemeinschaft (DFG) sponsors several
universities with Interdisciplinary Re-
search Grants for silicon carbide (SiC).
Primary among these are the University
of Erlangen-Nurnberg and the Friedrich
Schiller University in Jena, which are
concentrating on novel growth tech-
niques and electrical and optical mea-
surements. Siemens Research Laborato
ries in Erlangen, however, are concen
OCR for page R9
Preface
bating on power devices, as is Daimler-
Benz in Frankfurt for electric cars.
These laboratories as well as several
collaborating universities (i.e., Regens-
burg, Erlangen-Nurnberg, TH Aachen,
Ilmenau, and Fraunhofer Institut fur
Angenwandte Festkorperphysik in Frei-
burg) have large BMFT contracts for the
development of SiC power-devices.
France At least 10 university labora-
tories as well as LETI-Grenoble and
Thomson CSF (Paris) have government
funding for SiC high-frequency and
other devices.
Japan The committee was unable to dis-
cover critical details about the industrial
involvement of Japanese companies in SiC
development. However, emphasis appears to
be on optoelectronics with occasional men-
tion of high-temperature applications for the
automotive and aerospace industries. Optical
data transmission rates and storage densities
are enhanced by the use of shorter wave-
length laser light, which is synergistic with
high-temperature work because it requires
larger bandgap semiconductors. However,
the 1994 domestic Japanese SiC conference
drew 160 participants, many of whom were
interested in power devices. In the nitrides
~ i . e . , g a 1 1 i u m n i t r i d e , g a 1 1 i u m - i n d i u m - n i t r i d e ~
light sources, Nichia Chemical is producing
a 3 percent efficient blue light-emitting
diode. The interest in Japan in large bandgap
semiconductors for opto-electronics purposes
is highly visible, but an interest for power
electronics is growing. Japanese universities
that are active in SiC are the University of
Kyoto, the Kyoto Institute of Technology,
Osaka University, and the Electrotechnical
Laboratory in Tsukuba. Nitrides research is
also being pursued at Nagoya University.
Against this assessment of the national and inter-
national efforts to develop high-temperature semicon
o
1X
ductors, the goals of this study are to (1) identify the
technical barriers to the development and manufacture
of high-temperature semiconductor materials; (2)
determine the criteria for successfully packaging and
integrating new high-temperature semiconductors into
existing systems; (3) recommend future research
priorities; and (4) suggest additional possible applica-
tions and advantages.
The report is structured as follows. Chapter 1
discusses the need for high-temperature electronics.
Chapter 2 reviews the state of the art of wide band-
gap materials. The fundamental limit to high-tempera-
ture operation is the energy of the semiconducting
bandgap of the host material. By this measure, even
silicon with its "small" bandgap (1.1 eV) is not wide-
ly used near its limit of 300 °C (silicon as a high-
temperature material is discussed in Appendix A). A1-
though the technology has not been optimized for
high temperature and there are concerns about its
chemical stability, gallium arsenide (1.4 eV) does
offer the prospect of significantly higher temperature
in a mature technology (gallium arsenide is discussed
as a high-temperature semiconductor in Appendix B).
Alternative materials for yet higher temperatures must
be selected with care; larger gap is necessary but not
sufficient. Sulfide semiconductors have large band-
gaps but decompose at high temperatures. Thus,
Chapter 2 reviews the state of the art of materials
alternatives for which the prospect of robust high-
temperature operation has been confirmed. These
include SiC (2.4-3.3 eV depending on polylype),
gallium nitride (3.5 eV), aluminum nitride (6.2 eV),
boron-nitride (>6.4 eV), and diamond (5.4eV).
Chapters 3-6 discuss generic, technological issues
related to the design, fabrication, packaging, and
testing of high-temperature circuits and devices (spe-
cific case-studies are presented in Appendix C).
These chapters contain common elements that must
be established for any high-temperature electronics
technology to be possible. Chapter 7 presents recom-
mendations as to how to overcome critical hurdles on
the path to a family of robust high-temperature elec-
tronic devices.
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Acknowledgements
The committee expresses its appreciation to the following individuals for their presentations to the committee:
Dr. H.M. Hobgood, Westinghouse Science and Technical Center, Pittsburgh; Dr. Calvin Carter, Jr., CREE
Research Incorporated, Durham, North Carolina; Professor Peter Barnes, Auburn University; Mr. R.C. Clarke,
Westinghouse Science and Technology Center, Pittsburgh; Dr. Joseph S. Shor, Kulite Semiconductor, Leonia, New
Jersey; Dr. John Palmour, CREE Research Incorporated, Durham, North Carolina.; Dr. Dale M. Brown, General
Electric, Schenectady, New York; Professor Robert J. Trew, Case Western Reserve University, Cleveland; Dr.
Terrance Lee Aselage, Sandia National Laboratory, Albuquerque; Dr. Michael W. Gels, Lincoln Laboratory,
Massachusetts Institute of Technology; Dr. Jeff Glass, North Carolina State University, Raleigh; Dr. Asif Khan,
APA Optics, Inc., Blaine, Minnesota; Dr. Gary McGuire, Center for Microelectronic System Technologies, MCNC,
Research Triangle Park, North Carolina; Professor Hadis Morkoc, University of Illinois-Urbana; Dr. Nate Newman,
University of California, Berkeley; Dr. Harold West, Honeywell, Incorporated, Plymouth, Minnesota; Dr. Gerald
Wilt, AFOSR/NE, Boiling Air Force Base, Washington, D.C.; Professor Manijeh Razeghi, Director, Center for
Quantum Devices, Northwestern University; Dr. John A. Spitznagel, Westinghouse Science and Technology Center,
Pittsburgh; Professor Aris Christou, Chairman, Department of Materials and Nuclear Engineering, University of
Maryland, College Park; Dr. Richard Eden, Consultant, Thousand Oaks, California; Professor R. Wayne Johnson,
Electrical Engineering Department, Auburn University; and Dr. Philip L. Dreike, Sandia National Laboratory,
Albuquerque.
The committee acknowledges with thanks the contributions of Robert M. Ehrenreich, Senior Program Manager;
Jack Hughes, Research Associate; and Pat Williams, Senior Secretary, to the project.
x
OCR for page R11
Contents
EXECUTIVE SUMMARY
1 BACKGROUND
Survey I: Applications of High-Temperature Electronics by Industry, 7
Survey II: Applications by Thermal Environment, 12
Survey III: High-Temperature Electronics Applications by Complexity, 13
Summary, 14
STATE OF THE ART OF WIDE BANDGAP MATERIALS
Silicon Carbide, 15
Nitride Materials, 24
Diamond, 28
3 DEVICE PHYSICS: BEHAVIOR AT ELEVATED TEMPERATURES
High-Temperature Effects: Fundamental, Materials-Related Properties, 31
Predicting High-Temperature-Device Performance: Materials-Related Figures of Merit, 33
4 GENERIC TECHNICAL ISSUES ASSOCIATED WITH MATERIALS FOR
HIGH-TEMPERATURE SEMICONDUCTORS
Electrical Contacts, 39
Doping and Implantation, 40
Gate Oxides and Insulators, 43
Etching, 45
Defect Engineering and Control, 46
Yield, 47
Device reliability, 48
5 HIGH-TEMPERATURE ELECTRONIC PACKAGING
Chip Packaging, 51
Substrates, 53
Thick-Film and Thin-Film Metallization9 53
Component Attachment, 55
Interconnection, 56
Second-Level Packaging, 57
Summary, 58
X1
7
15
31
39
51
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6 DEVICE TESTING FOR HIGH-TEMPERATURE ELECTRONIC MATERIALS
Short-Term Constant-Temperature Tests, 61
Constant-Temperature Life Tests, 62
Thermal-Cycling Tests, 62
Future Requirements for High-Temperature Testing, 63
CONCLUSIONS AND RECOMMENDATIONS
General Conclusions and Recommendations, 65
Materials-Specific Conclusions and Recommendations, 67
References
Appendix A: Silicon as a High-Temperature Material
Appendix B: Gallium Arsenide as a High-Temperature Material
Appendix C: High-Temperature Microwave Devices
61
65
71
81
87
93
Appendix D: Biographical Sketches of Committee Members 119
xii
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Figures
1-1 Schematic of a hypothetical drive-by-wire system for an automobile with computerized
traction control, steering, and suspension
Log-log plot of the complexity of some example applications as a function of temperature
Average values of the optical constants of SiC from the vacuum ultraviolet to the middle infrared
Calculated band structure of 3C-SiC
Calculated band structure of 2H-SiC
Summary of the experimentally observed excitor bandgaps and their temperature variation
for the different SiC polytypes
2-5 Thermal conductivity of two single crystals of SiC
2-6 Schematic showing the basic elements of the modified sublimation process
2 7 Schematic of a typical SiC CVD growth chamber
2-8 Band structure of hexagonal and cubic modifications of A1N
2-9 Band structure of hexagonal and cubic modifications of GaN
2-10 Band-structure calculation of diamond
2-11 Thermal conductivity of two Type IIa diamonds
3-1 Calculated electron mobility as a function of temperature for undoped 6H-SiC and 3C-SiC
3-2 Calculated electron mobility as a function of temperature for GaN doped e-type, 10~7 cm~3
Intrinsic carrier density for silicon, GaAs, and SiC
Decrease in silicon bandgap with increasing temperature
Calculated reverse leakage current densities in pen junctions of various materials
Variation in threshold voltage versus temperature for n- and p-channel MOSFET devices
Operating temperatures for different devices per material
Schematic of the device structure for a AlN/AlxGa~ xN SISFET
Increase in resistivity of unintentionally doped AlxGa~ xN with increasing aluminum mole fraction
Decrease in insulation resistance as a function of temperature
5-2 Reduction from nine to three electrical path segments between two integrated circuits
with multichip module technology
6-1 Variations in threshold voltage for p- and e-type silicon MOSFETs with temperature
6-2 Drain characteristics of a SiC inversion-mode MOSFET at 650 °C
A-1 Reduction in large junction isolation areas by the use of trenches and SOI
A-2 Leakage currents as function of temperature for three types of n-MOS transistors with
gate lengths of 2 microns
· . ~
x~'
8
13
17
18
18
19
20
22
23
26
27
29
29
32
32
32
33
35
36
37
44
45
52
59
61
61
83
83
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Schematics of the dielectric isolation material process flow and the bonded wafer
material process flow
A-4 Open-loop gain as a function of temperature
B-1 GaAs MESFET and silicon MOSFET drain leakage currents
B-2 MESFET transconductance, am, after three-hour anneals at various temperatures
B-3 Diffusion barrier constructed of nine alternating layers of electron-beam evaporated
tungsten and silicon
B-4 Comparison of conventional MESFET with MESFET using temperature-hard ohmic contacts,
buried p-type channel implants, and gate sidewall spacers
B-5 MESFET showing on/off current ratio decreasing from 106:1 at room temperature
to near 20:1 at 400°C
High-temperature MESFET incorporating modifications to standard process
Operating characteristics of MESFET structure shown in Figure B-6
Contours of normalized power dissipation on the gain-efficiency plane
Enhancement- and depletion-mode MOSFETs
Structure of a bipolar junction transistor
Simulated microwave performance of SiC BJTs
Comparison of SIT with MESFET: (a) potential gate barriers established, (b) resulting
current-voltage curves for SIT; (c) generic MESFET I-V curves
Structure of the Junction Field Effect Transistor (JFET)
Typical current-voltage curves for a JFET at various temperatures
Structure of an inverted JFET in SiC
C-9 Measured small signal current and unilateral gain for SiC MESFETs
C-10 IMPATT diode performance compared with projections for wide bandgap semiconductors
C-l l Material structures and electric field profiles possible for IMPATT diodes
C-12 A simplified equivalent circuit for an IMPATT diode embedded in a microwave circuit
C-13 'a' contours for MESFETs of silicon, GaAs, silicon carbide, and gallium nitride
C-14 Calculated locus of drain-current saturation for (a) silicon carbide, (b) silicon, and
(c) GaAs (with and without parasitic series resistance)
C-15 A simple model for ohmic contact and channel resistance contributions to MESFET
source resistance
C-16 Contact resistance calculated as a function of contact length for three materials
C-17 Contours of constant Z plotted on rc-Rsq plane
C-18 Representation of current-voltage curves for a MESFET and typical loadlines for
Class A operation
C-l9 Small signal equivalent circuit for a MESFET
C-20 Contours of constant temperature rise in the GaAs MESFET channel
C-21 Contours of constant temperature rise in the SiC MESFET channel
C-22 A MODFET transistor with a two-dimensional electron gas at the interface
between GaN and AlGaN
B-6
B-7
C-1
C-2
C-3
C-4
C-S
C-6
C-7
C-8
x~v
84
85
88
88
89
89
90
90
91
94
96
97
98
98
100
101
101
103
104
104
105
106
107
108
109
110
111
112
113
114
115
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Tables
2-1 Comparison of Semiconductor Properties
2-2 Notations for Selected SiC Polytypes
Exciton Binding, Nitrogen Ionization, and Valley-Orbit Splitting Energies and
Effective Mass for SiC Polytypes
Comparison of Normalized Figures of Merit of Various Semiconductors for High-Power
and High-Frequency Unipolar Devices
Selected Ohmic Contacts to e-Type 6H-SiC and Measured Contact Resistivities at
Room Temperature
Selected Ohmic Contacts to p-Type 6H-SiC and Measured Contact Resistivities at
Room Temperature
4-3 Additional Ohmic Contact for SiC
4-4 Ohmic Contacts for GaN
5-1 Properties of Ceramic AlN, Ceramic SiC, Glass + Ceramics as Compared with
90 percent Alumina
Metallizations for AlN Substrates
Dielectrics for A1N Substrates
Summary of Properties of Metallizations for AlN
Typical Cofired Metals
6-1 Short-Term Constant-Temperature Tests
Constant-Temperature Life Tests
Summary of Room-Temperature DC Gain for Various Field Effect Transistors of SiC
Assumed and Calculated MESFET Current-Voltage Model Parameters
Listing of Several Refractory Metallizations on SiC and their Contact Resistivities
Assumed and Calculated MESFET Power Model Parameters
xv
16
17
21
34
40
41
42
43
54
55
56
57
58
62
63
102
108
111
112
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