Analysis of high voltage operation of gallium arsenide photoconductive switches used in high power applications

An opposed-contact photoconductive semiconductor switch, with a n(+) region next to the cathode electrode has been simulated. Physical conditions during the pulse charging state, prior to high power switching, are analyzed in order to explain the increased hold-off characteristic of such devices. Results show that the introduction of the n(+) region near the cathode inhibits the flow of electrons at the n(+)/semi-insulating interface until very high fields are reached. The formation of trap-filled regions near the contacts and the resultant inhomogeneous device characteristics that lead to breakdown are thereby shifted to higher voltages. Thus, for switches with a n(+) region next to the cathode, the breakdown voltage due to unstable filamentary conduction is also increased beyond those achieved previously, allowing for higher power operation. (C) 1999 American Institute of Physics. [S0021-8979(99)05315-3].