Mesa-isolated InGaAs avalanche photodiode damage by ionizing radiation

Abstract

InGaAs avalanche photodiodes (APDs) fabricated from epitaxial material by etching detector mesas and encapsulating the etched mesas under bisbenzocyclobutene (BCB) resin were irradiated by Co-60 gamma-rays to assess their sensitivity to a total ionizing dose of 200 krad(Si). A low-excess-noise APD design with a multi-stage avalanche gain region was tested. Ninety-six identical 20-μm-diameter APDs were characterized to assess the response of the design to ionizing radiation. The APDs were not under bias during irradiation. Damage to the APDs was characterized by measuring the change in room temperature dark current following irradiation, at a reverse bias for which the average avalanche gain is M=10. No significant increase of dark current was observed following gamma irradiation: the average increase was 5% and the standard deviation for the measurement was 10%.