Using a "spatial correlation" model with a Gaussian correlation function we have for the first time quantitatively explained the broadening and asymmetry of the first-order longitudinal-optic phonon Raman spectrum induced by alloy potential fluctuations. The systems studied were the representative alloy semiconductors ${\mathrm{Ga}}_{1-x}{\mathrm{Al}}_x\mathrm{As}/\mathrm{GaAs}$ and ${\mathrm{Ga}}_{0.47}$${\mathrm{In}}_{0.53}$As/InP. This analysis provides important insights into the microscopic nature of the alloy potential fluctuations.

• Received 8 November 1983

DOI:https://doi.org/10.1103/PhysRevLett.52.1822