| Citation | Dr. Hilsum is noted for his contributions to the science of compound semiconductors. His standing is shown by the number of invited papers contributed to the International Semi-conductor Conferences. He published some of the earliest papers on electronic transport in InSb and has followed this with many on GaAs. Both of these compounds have been central to the understanding of the physics of semiconductors and also in yielding useful devices. It is in the application of hot-electron effects that Dr Hilsum's most distinguished contribution has occurred. After directing the early work on GaAs (for which he deserves much of the credit for the strong competitive position which the U.K. now has in GaAs devices) he predicted the existence of negative resistance effects through the transfer of conduction electrons from one minimum of the energy band structure to another which changes the dynamics of the moving charge carrier. His contribution ranks with four other workers in the world, who, together, were about equally responsible for the ultimate discovery of the "Gunn effect" oscillator - a semiconductor microwave source now in general use. Gunn's observations of high frequency oscillation contained elements of surprise and the effects were not correctly understood at the time - that the explanation was already contained in Dr. Hilsum's prediction is now recognised. Dr. Hilsum has performed much successful work on device development as attested by the patents issued in his name. |