Raman spectroscopy of GaAs and InGaAs under pressure

Strained layers of InGaAs on GaAs have been studied by Raman scattering under high pressure. More accurate values are given for the frequencies of the LO and TO phonons in GaAs and their pressure dependence. The frequency and pressure dependence of the LO GaAs-like phonon in 20% InGaAs is also reported. It is shown that the Raman shift at the phase transition at high pressure is a valuable diagnostic, allowing comparisons of different experiments. The phase transition pressure of the ternary alloy is consistent with linear interpolation between the binary compound values.