InAs infrared avalanche photodiodes

InAs p-n junction photodiodes with high breakdown voltages and extremely low reverse-leakage currents up to the breakdown voltage have been developed. Because of the low current and high breakdown voltage, we have observed quantum efficiencies greater than unity in reverse-biased InAs photodiodes. These gains are attributable to the avalanche carrier multiplication in the reverse-biased p-n junction. Carrier multiplication gains of greater than 100 have been measured in these devices. Relative values of the ionization coefficients for both electrons and holes can be determined by measuring the photoresponse as a function of reverse bias. The photoresponse obtained with penetrating radiations varies greatly with the bias, and the increase in the response in the high bias region appears to be caused by the Franz-Keldysh effect; i.e., the optical absorption coefficient changes with the electric field in the reverse-biased p-n junction. Detailed measurements of these studies will be discussed.