TEMPERATURE-DEPENDENCE OF THE RAMAN-SPECTRUM OF ALXGA1-XAS TERNARY ALLOYS

We have studied the effect of the temperature on the first-order Raman spectra of AlxGa1-xAs alloys. The temperature induced frequency shift is studied over the full composition range between 300 and 650 K. It is found that the frequency temperature coefficient, d omega/dT, is hi gher for AlAs-like modes than for GaAs-like modes and it increases wit h x. Linewidth and frequency shift data were analyzed in terms of anha rmonicity, thermal expansion, and cation dilution. Anharmonicity was f ound to be the dominant term in the variation of the temperature depen dence of the frequency of AlAs modes for different alloy compositions, while thermal expansion has a high influence on GaAs modes. The Linew idth data are interpreted in terms of the contribution to the Raman sp ectrum of phonons with q not equal 0 and cation dilution. [S0163-1829( 98)07339-1].