Characterization of impact ionization engineered InGaAs avalanche photodiodes

Abstract

The U.S. Naval Research Laboratory (NRL) is characterizing InGaAs avalanche photodiodes (APDs) with internal structures engineered to reduce dark counts and ionization coefficient ratio (keff). Recently, much progress has been made in the use of APDs in linear mode for photon counting applications.1 However, the best results in linear mode single photon counting in InGaAs devices have been obtained by cooling the devices well below 200 K to reduce dark current. The single photon counting capability is due to the high gain available in the tail of the APD gain distribution, and this high gain tail is enhanced by reducing the ionization ratio (keff) and dark noise.2 Since recent promising results in linear mode APD photon counting have involved engineering the APDs to reduce keff, it is likely that these devices will also perform much better than standard APDs in free space lasercomm applications at temperatures which can easily be reached by thermoelectric coolers, or even uncooled, due to the keff reduction. NRL has obtained several InGaAs APDs of both the standard design and of a new design using impact ionization engineering from OptoGration, Inc. of Wilmington, MA. Some results of characterization of these APDs will be presented.