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 ON state there are many excess carriers in the inner layers of the device. Reversing the anode voltage removes these carriers, turning the device off. The behavior of a PnpN structure after reversing the anode voltage essentially depends on the width of the n base. For a wide n base, negative anode voltage has little effect on carrier removal. In the 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 from the device. This allows decrease in turn-off times by several orders 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.