Electron irradiation effects on photoconductive semiconductor switches (PCSSs) used in sub-nanosecond transient generators

摘要: Radiation-induced damage occurs in GaAs photoconductive semiconductor switches used sub-nanosecond transient generators when subjected to 600 keV and 6 MeV electron irradiation. These are made from semi-insulating (SI) compensated material through a EL2/carbon compensation mechanism, the liquid encapsulated Czochralski process. New defect levels formed as result of non-ionizing energy loss (NIEL) The formation new device alters compensating balance between existing deep level EL2 trap/donors carbon acceptors, changes properties. As result, two important parameters adversely affected-the hold-off voltage switch at pulse-charging (off) state, rise time during conduction (on) state. shifts lower value since there more trap-filled regions available that can fill up alter homogenous nature material. Unstable filamentary then leads premature breakdown. with trap levels, states induced by irradiation will further contribute delay switch. determines maximum transferred load. mechanism its effects on characteristics depend Intrinsic material, or other than donor shallow acceptor balancing process not expected behave similarly. Simulation results higher bias show marked degradation current-voltage (I-V) characteristic increases kilovolt range is similar trap-dominated semiconductors. An initial sublinear current regime low followed super-linear flow bias, agreement earlier observations.