No abstract

The growth, by MOVPE, of a range of antimonide-based material systems suitab!e for providing devices responsive to 2-4 pm wavelength radiation is reported. Photodetectors with external quantum efficiencies of 60% at 2.2 pm have been fabricated from an InGaSb homojunction. In order to examine the possibility of tuning the wavelength of emission or detection by using a strained single quantum well (ssow) of InGaSbIGaSb this has been grown in the depletion region of a GaSb homojunction. need for conventional doping. Using the crossed-gap alignment of InAsiGaSb we can form a diode-like structure. The most promising devices have a turn-on voltage VTo of 0.7V (1 mA), and a typical reverse voltage V, = -12V (0.1 mA) and a best V, of -12 V (IO PA) for a 100 pm diameter device with some evidence of avalanche breakdown in the structure.Abrupt doping junctions have been formed between GaSb and GaAs:Si substrates. The mismatch between the layers is ameliorated by using a low-temperature buffer layer to improve the interface. Avalanche breakdown starts at -4.5 V in these structures and reverse bias currents of