A novel material deposited by molecular beam epitaxy at low substrate temperatures using Ga and As4 beam fluxes has been used as the active layer for a high-speed photoconductive optoelectronic switch. The high-speed photoconductive performance of the material was assessed by fabricating two devices: an Auston switch and a photoconductive-gap switch with a coplanar transmission line. In a coplanar transmission line configuration, the speed of response is 1.6 ps (full width at half maximum) and the response is 10 to 100 times greater than that of conventional photoconductive switches. Since the material is compatible with GaAs discrete device and integrated circuit technologies, this photoconductive switch may find extensive applications for high-speed device and circuit testing.

Enhanced quantum efficiencies have been obtained for Au-InP internal photoemission detectors using grating coupling of incident radiation into surface plasma waves confined to the air-metal interface. Enhancements of over a factor of 30 are observed at the resonance coupling angles. A model calculation of the surface plasma wave coupling is in good qualitative agreement with the experiment. Time-resolved response measurements show that the present detectors are capacitance limited; picosecond response speeds are attainable with lower carrier concentration materials and smaller active areas.

The electron-coupled phonon spectrum o? F 9 X, and /i* have been determined for polycrystalline and high-purity, single-crystal niobium from tunnel junctions fabricated with three different counterelectrodes. All spectra compare well with phonon spectra extracted from neutron-scattering experiments. Values of X are BCS-like and M* is always negative. Computer-modeling studies describing a niobiumlike material cannot generate an acceptable set of strong-coupling parameters.