Bistable photoconductive switches particularly suited for frequency-agile, radio-frequency sources

Abstract

A photoconductive switching device is disclosed that has an enhanced speed of response so that its closed (low) and open (high) resistive states are obtained in response to optical illumination in the less than nanosecond regime. The enhanced speed of response is achieved by neutron irradiation of a material preferably comprising GaAs:Si:Cu. An application of the improved photoconductive switching devices is disclosed which allows the realization of a high-power, frequency-agile RF source topology.

What is claimed is: 
     
       1. A method of enhancing the speed of response of photoconductive switching device from its low to its high electrical resistance state in response to the presence of photon energy, said photoconductive switch device comprising a GaSa:Si:Cu material formed by a process of thermally diffusing said Cu into said GaAs, said method comprising: (a) exposing said thermally diffused GaAs:Si:Cu material to a predetermined intensity of neutron radiation supplied from a source having an energy spectrum from about 10 keV to about 1 MeV and defined by a predetermined range of fluence from about 2.5×10 15  cm -2  to about 4×10 15  cm -2 , said thermally diffused GaAs:Si:Cu material being held at a temperature less than about 100° C. during said neutron irradiation; and   (b) forming an electrical contact at opposite ends of the same surface of said thermally diffused GaAs:Si:Cu material and repeating step (a) before and after step (b).   
     
     
       2. A method of enhancing the speed of response of photoconductive switching device from its low to its high electrical resistance state in response to the presence of photon energy, said photoconductive switch device comprising a GaAs:Si:Cu material formed by a process of thermally diffusing said Cu into said GaAs, said method comprising: (a) exposing said thermally diffused GaAs:Si:Cu material to a predetermined intensity of neutron radiation defined by a predetermined range of fluence; and wherein said thermally diffused GaAs:Si:Cu material is held at a temperature less than about 100° C. during said neutron irradiation.