PHOTOCONDUCTIVITY IN HOMOJUNCTION INTERNAL PHOTOEMISSION FAR-INFRAREDDETECTORS

A photoconductivity generation mechanism in homojunction interfacial w orkfunction internal photoemission (Hn;VIP) far-infrared detectors has been studied. A simple model is proposed and shows that the photocond uctive gain of internal photoemission detectors is less than but close to unity and independent of the number of the emitter layers, while t he current responsivity is proportional to the number of emitter layer s. The results are in good agreement with the p-GaAs HIWIP experiments . The response time of the p-GaAs HIWIP detectors was estimated to be 20 ps from the bias-dependent responsivity measurements, which shows t he suitability for high-speed heterodyne applications. (C) 1998 Elsevi er Science B.V. All rights reserved.