PHOTOCONDUCTIVITY AND INFRA-RED QUENCHING IN CHROMIUM-DOPED SEMI-INSULATING GALLIUM ARSENIDE

Photoconductivity measurements in samples of melt-grown chromium-doped semi-insulating GaAs have shown an impurity peak response at 0·87 ev. Evidence is presented that the transition responsible for the peak is an electron transition from compensated chromium acceptor levels to the conduction band. Infra-red quenching experiments confirm that the chromium level, deduced to be approximately 0·79 ev from the conduction band, does indeed behave as a compensated deep acceptor level.