Structural and luminescence properties of InAs0.94Sb0.06 alloy grown via MOVPE

We report on the characterization of an epitaxial layer of InAs0.94Sb0.06 grown on semi insulating GaAs by metal organic vapour phase epitaxy (MOVPE). Transmission electron microscopy, x-ray diffraction, photoluminescence and photoconductivity spectroscopy were used to characterize the layers in terms of its structural and luminescent properties, with emphasis on residual stress/strain, extended defects like dislocations, band gap energies and impurity states. Temperature dependant Hall measurements were also performed. The composition of the layer as well as strain relaxation was confirmed by High resolution X-ray diffraction. Photoluminescence produced a broad emission peak which was shown to be a convolution of extrinsic recombination and band-to-band transitions. A comparison between photoluminescence and photoconductivity results confirmed this analysis. The absorption edges, determined from photocurrent spectroscopy measurements at different temperatures, were fitted with an Einstein single oscillator model, yielding a 0 K band gap energy of 355 meV. Hall mobility results showed a peak mobility of 9.5 × 103 cm2 /V.s at 115 K; results were fitted with a two-layer Hall model yielding a bulk peak mobility of 22.4 × 103 cm2 /V.s at 88 K, with a majority donor carrier concentration of roughly 5 × 10-15 cm-3. These results continue to show that InAs1-xSbx has great potential for use within mid-wave infrared detectors, however further improvement in deposition growth is still needed for final device manufacture.