Space charge formation in chromium compensated GaAs radiation detectors

Space charge formation in chromium-compensated GaAs sensors is investigated by the laser-induced transient current technique applying pulsed and DC bias. Formation of non-standard space charge manifested by an appearance of both negatively and positively charged regions in DC biased sensors was revealed during 5 ms after switching bias. Using Monte Carlo simulations of current transients we determined enhanced electron lifetime tau= 150 ns and electron drift mobility mu(d)= 3650 cm(2)Vs(-1). We developed and successfully applied a theoretical model based on fast hole trapping in the system with spatially variable hole conductivity.