Photoluminescence from solution-grown AlxGa1-xSb alloys

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Abstract
Atomic absorption spectroscopy studies were carried out on single crystals with x up to 0.67. The composition increases monotonically with increasing Al:Sb atomic ratio in the solution. The composition is not in proportion to the ratio Al:Sb, i.e. the rate of the increase reduces as x increases. Electron-beam microprobe X-ray microanalysis has certified uniformity of the composition of mu m order. Photoluminescence spectra have been measured at 80K. The spectrum usually has two peaks. The higher energy peak is mainly in the small x region, while the lower one becomes dominant as x increases. As the concentration of Al increases the spectrum shifts towards the higher energy region, and simultaneously the half-value bandwidth of the spectrum becomes broader and the intensity drastically decreases. The broadening may be ascribed to fluctuation of energy state due to perturbed disorder arrangement of group III atoms in the lattice. The peaks are concluded to be due to pair recombinations between impurity levels; Si-donor and residual acceptor for the higher energy peak, and Si-donor and Si-acceptor for the lower energy peak.