EXPERIMENTS AND MODELING OF THE PHOTOCURRENT RESPONSE OF GAAS-MESFETS

One micron technology GaAs MESFETs have been exposed to a transient radiation environment at the Rensselaer Gaerttner Linear Accelerator Laboratory and modeled by computer simulation using a modified version of the PISCES-IIB semiconductor device simulation code and the TRIGSPICE circuit simulation code. The MESFETs were tested in steady-state conditions, with short (20 ns) radiation pulses, and with short pulses on devices that had received a prior dose of gamma, neutron or neutron-plus-gamma irradiation. Parasitic bipolar action was observed in the short pulse testing in unexposed devices. Previously unreported transient failure was observed in the neutron pre-irradiated devices only. The threshold for this failure was consistent with the level of severity of prior irradiation. Steady-state photocurrent and the parasitic bipolar transistor are modeled and explained on the basis of physical mechanisms. © 1990 IEEE