Infrared Photo Transistor Based on Inter-Valence Sub-Band Transition

A novel quantum well infrared photo transistor, which we call QWIPT, is proposed. By taking the advantage of the almost perfect alignment of the conduction band in GaAsSb/InAlAs system, it is possible to integrate such quantum wells into a QWIPT to improve the optical gain and, therefore, the detectivity of the p-QWIP. We expect, by incorporating molecular beam epitaxy growth interruption scheme, to suppress background noise much further and greatly improve 77 K imaging array performance. The Phase I effort will be directed toward the realization of strain-balanced GaAsSb/InAlAs quantum wells. High-sensitivity, larger area (256x256 or larger) p-QWIP imaging arrays based on mature GaAs and InP processing technologies will be implemented in Phase II. The proposed design will enhance the emitter injection efficiency (in an npn phototransistor) and, therefore, improve the detectivity and optical gain. This technology should considerably speed the development of higher sensitivity, larger area, more reliable infrared detector components/arrays for defense application.