Bandgap engineering of InSb by N incorporation by metal-organic chemical vapor deposition

Bandgap engineering is necessary for the application of InSb in long wavelength infrared photodetection. InSbN alloys hetero-epitaxially were therefore deposited on GaAs substrate by metal-organic chemical vapor deposition (MOCVD), expecting a large band gap reduction by N incorporation for long wavelength infrared photodetection. The effects of post annealing treatment on the structural and optical properties of the grown InSbN alloy have been well studied. Photoluminescence measurement (PL) indicated that the longest PL wavelength obtained at 10 K is ∼7.2 μm for the InSbN alloys, which manifests an extension of PL wavelength as large as ∼ 1.8 μm in comparison to the undoped InSb epilayers, suggesting a successful band gap reduction by the N incorporation. X-ray photoelectron spectroscopy (XPS) measurements show that three kinds of nitrogen bonds co-exist in the alloys and their percentages vary with annealing conditions. This observation can explain the peak shifts of X-ray diffraction (XRD) and PL spectra. The comparison to our previous works reveals that the InSbN alloys grown on GaAs substrate can achieve more nitrogen incorporation and band gap reduction than the alloys grown on InSb and GaSb substrates.