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Devices and desires in the 2-4 mu m region based on antimony-containing III-V heterostructures grown by MOVPE

1993; IOP Publishing; Volume: 8; Issue: 1S Linguagem: Inglês

10.1088/0268-1242/8/1s/085

1361-6641

A. Aardvark, Guy-Germain Allogho, G. Bougnot, J.P.R. David, Alain Giani, S. K. Haywood, G. Hill, P. C. Klipstein, F. Mansoor, N. J. Mason, R. J. Nicholas, F. Pascal‐Delannoy, M.A. Pate, Lalitha Ponnampalam, P.J. Walker,

Semiconductor materials and interfaces

The growth, by MOVPE, of a range of antimonide-based material systems suitable for providing devices responsive to 2-4 mu m wavelength radiation is reported. Photodetectors with external quantum efficiencies of 60% at 2.2 mu m 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 (SSQW) of InGaSb/GaSb this has been grown in the depletion region of a GaSb homojunction. These novel heterostructures have been grown to produce devices without the need for conventional doping. Using the crossed-gap alignment of InAs/GaSb the authors can form a diode-like structure. The most promising devices have a turn-on voltage VTO of 0.7 V (1mA), and a typical reverse voltage VR=-12 V (0.1 mA) and a best VR of -12 V (10 mu A) for a 100 mu m 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 <10 mu A at up to 2 V from unintentionally doped GaSb (uGaSb) with a carrier concentration of 1016 cm-3 p. Schottky barriers are an alternative to p/n junctions, but they cannot be made at all on uGaSb because of the low barrier height, which is of the order of 0.2 eV. We have overcome this problem using a thin capping layer of highly dislocated GaAs. Surprisingly this has been successful for both regrowth on older structures and contiguous in situ growth.