Bulk avalanche semiconductor switch using partial light penetration and inducing field compression

摘要

A switch using an improved method of optically-triggered avalanche breakdown which can produce pulses of 100 picoseconds duration that can deliver five kilovolts into 50 ohms using a standard laser diode. A semiconductor block is provided with contacts on opposing sides across which a high-voltage less than the avalanche breakdown voltage is applied. The semiconductor block is then irradiated with electromagnetic radiation. The wavelength of the radiation and the absorption co-efficient of the semiconductor block are chosen so that the absorption depth of the majority of the radiation is less than the distance between the contacts. This results in a photoconduction area where absorption occurs, thus applying most of the high voltage across the distance beyond the photoconduction area. This provides field compression and generates an avalanche breakdown field across the remaining distance of the semiconductor block. Fast switching of large currents is obtained through the dual use of photoconduction as a trigger and subsequent avalanche conduction.