Growth of room-temperature "arsenic free" infrared photovoltaic detectors on GaSb substrate using metamorphic InAlSb digital alloy buffer layers

The authors demonstrate and characterize type-II GaSb quantum dot ͑QD͒ formation on GaAs by either Stranski-Krastanov ͑SK͒ or interfacial misfit ͑IMF͒ growth mode. The growth mode selection is controlled by the gallium to antimony ͑III/V͒ ratio where a high III/V ratio produces IMF and a low ratio establishes the SK growth mode. The IMF growth mode produces strain-relaxed QDs, where the SK QDs remain highly strained. Both ensembles demonstrate strong room temperature photoluminescence ͑PL͒ with the SK QDs emitting at 1180 nm and the IMF QDs emitting at 1375 nm. Quantized energy levels along with a spectral blueshift are observed in 77 K PL. Transmission electron microscope images identify the IMF array and crystallographic shape for both types of QD formation. Atomic force microscope images characterize QD geometry and density.

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