semiconductors, for example, gallium arsenide. Some of these studies constituted the Ph.D. theses of two graduate students at the University of Pittsburgh. Bob expanded these studies to include uniaxial stress experiments. His work and that of others elucidated the energy band structure of germanium and silicon. He showed that, because of the multivalley nature of the conduction band structure in silicon and germanium, the free energy can be lowered by strain that reduces the electron energy due to transfer among the valleys. This causes a reduction in some of the elastic constants in heavily doped n-type silicon and germanium. He experimentally verified the existence and magnitude of the predicted effect several years later.
While at Westinghouse, Bob worked in several other areas of semiconductors, including thermal conductivity, thermoelectric power, and the effects of strain. He and his colleagues observed a very large magnetoresistence in n-type (electrons carry the current as opposed to holes) indium antimonide, which amounted to a metal-insulator transition. He spent the fall quarter of 1957 at the University of Chicago as a visiting scientist on leave from the Westinghouse Research Laboratory. Bob spent his time there studying interpretations of measurements of atomic diffusion in solids at high pressure. His work showed that simple models by and large explain the pressure effects.
In 1960, Bob resigned from Westinghouse to join the new and rapidly expanding IBM Research Laboratory in Yorktown Heights, Westchester County, New York. He spent the remainder of his career there, first as a research manager, then as a research staff member, and finally as a research staff member emeritus. Bob actively engaged in research right up to the time of his death. His last paper was published posthumously.
His first assignment at IBM was to manage a small group involved at various times in work on novel devices, including transistor engineering, the physical basis of the Gunn effect, solar cells, process instrumentation and gas panel displays, and ion-implanted superconducting devices. The group included