Photodiodes for a 1.5-4.8 mu m spectral range based on type-II GaSb/InGaAsSb heterostructures

Long-wavelength photodiodes based on LPE-grown type-II heterostructures in lattice-matched GaSb/InGaAsSb/GaInAsSb and GaSb/InGaAsSb/AlGaAsSb systems w ere fabricated and studied. Band energy diagram engineering for heterostruc tures with wide- and narrow-gap layers allows the photodiode parameters to be controlled by varying the conditions at heterointerfaces. Electrical and photoelectric characteristics and the dark current mechanisms in the heter ostructures were investigated. The optimal photodiode structure was selecte d that consists of two type-II broken-gap heterojunctions and one p-n-junct ion in the narrow-gap active layer. Room-temperature detectivity D-lambda* = 4.1 x 10(8) cm Hz(1/2)/W at lambda = 4.7 mum was obtained. Type-II hetero structures may help develop high-efficiency uncooled photodiodes for the 1. 6-4.8 mum range for gas analysis, environmental monitoring, and also the di agnostics of combustion and explosion products. (C) 2001 MAIK "Nauka/Interp eriodica".