REVERSE RECOVERY OF A GAAS OPTOELECTRONIC THYRISTOR

Results of numerical simulation of reverse recovery processes in a two -terminal GaAs optothyristor are presented. In the highly conducting O N state there are many excess carriers in the inner layers of the devi ce. Reversing the anode voltage removes these carriers, turning the de vice off. The behavior of a PnpN structure after reversing the anode v oltage essentially depends on the width of the n base. For a wide n ba se, negative anode voltage has little effect on carrier removal. In th e case of a narrow n region, penetration of an electric field into the p base is responsible for a fast removal of slowly diffusing holes fr om the device. This allows decrease in turn-off times by several order s of magnitude over traditional two-terminal devices.:The thyristor is switched off completely after the time interval, when all holes have been evacuated from the p base. Reverse-recovery time for this regime of ''n-base punchthrough'' is calculated in terms of device parameters . (C) 1996 American Institute of Physics.