AlGaN material structures for a two color UV imager

Abstract

GaN/AlGaN dual-band detectors responding in UV and IR regions based on interband and intraband transitions have been developed. These dual-band detectors simultaneously detect UV radiation in the 250–360 nm and IR radiation in the 5–14 μm regions with near zero spectral cross talk. MOCVD growth and process conditions were optimized for GaN and AlGaN thin films as well as for device structures to improve the efficiency of devices. Also, by etching out the top-contact layer, it was shown that the UV response of the detector can be enhanced. Having separate UV- and IR-active regions with three contacts (one common contact for both regions) allows the separation of the UV and IR generated photocurrent components, identifying the relative strength of each component. This is an important development in UV–IR dual-band applications such as fire–flame detection, solar astronomy, and military sensing, eliminating the difficulties of employing several individual detectors with separate electronics–cooling mechanisms.