The GaAlAsSb quaternary and GaAlSb ternary alloys and their application to infrared detectors

Abstract

GaAlAsSb quaternary alloys and GaAlSb ternary alloys have been grown by liquid phase epitaxy (LPE) at 550°C and 450°C, respectively. The material compositions and epitaxial structures are suitable for fabricating photodiodes sensitive in the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1.0-1.8 \mu</tex> m wavelength range. Various avalanche photodiode structures fabricated in these materials are discussed. The ion implanted GaAlAsSb APD's exhibit a high gain of 100, 82 percent quantum efficiency, and a FWHM of 400 ps. The heterojunction GaAlAsSb APD's have a gain of 40, 92 percent quantum efficiency, and a FWTM of 150 ps. The only remaining material problem which limits the performance of these devices is the high-surface leakage current.