Mid Infrared InP-based Photodiodes operating at/near Room temperature

摘要

Photon detectors operating in the MWTR. (2 to 5 μm) are important in applications such as pollution detection, industrial process monitoring, chemical forensics, chemical and biological warfare, and non-invasive medical diagnostics. Current photon detectors in the MWIR use two different types of optical transitions: inter-subband and band-to-band. For inter-subband photodetectors, QWIPs are the mainstay technology. To get reasonable detectivities, these devices must be operated at cryogenic temperatures, which significantly increase system costs. For detectors using band-to-band transitions, HgCdTe is the predominant material system used in devices today. HgCdTe focal plane arrays used for imaging applications often suffer from material non-uniformity and low yield. Our research goal is to develop InP-based devices as an alternative for MWIR detection. The approach we have pursued for longer wavelength detection on InP is a type-II superlattice consisting of Ga{sub}xIn{sub}(1-x)As and GaAs{sub}ySb{sub}(1-y) alloys. These structures provide two advantages for MWIR detection: large (greater than 700 meV) direct band-gaps, which should lead to a lower thermal carrier generation rate and the ability to adjust the detection wavelength by changing the compositions of GaInAs and GaAsSb and their thickness, in the superlattice