Extended wavelength InGaAs detectors-recent progress in new materials for bandgap wavelengths λg>1.65 μm

Applications for night vision, remote sensing and spectroscopy have increased interest in the 1.65 μm to 2.5 μm wavelength band. New detectors and detector materials with access to this range of wavelengths are particularly desirable due to the limited utility of HgCdTe, InAs, InSb, and lattice-mismatched InGaAs devices. HgCdTe is plagued by material growth issues and the narrow bandgaps of InAs and InSb result in detectors with large dark currents at room temperature. Furthermore, GaInAsSb devices grown on GaSb substrates have dark currents in the microamp range for detectors as small as 100 μm diameter. The most successful commercial detector in this wavelength band is lattice-mismatched InGaAs; which, when grown on buffer layers of relaxed InAsP, results in detectors with acceptable dark currents and high bandwidth. However, residual defects in the epitaxial layers, as well as the lack of integration capability with InP electronics, necessitate the exploration of novel materials and device structures