Effect masses and non-parabolicity in GaxIn1-xAs

Measurements are reported of frequency- and temperature-dependent cyclotron resonance in the ternary alloy Ga x In 1-x As, close to its lattice match with InP. The band-edge effective mass is found to be 0.041 m 0 for x=0.47, in agreement with earlier measurements, but it is found that the non-parabolicity of the conduction band is approximately double that expected on the basis of k.p perturbation theory. This is thought to be due to alloy disorder. Magnetophonon resonance was also observed, giving a further measurement of the effective mass, together with the first observation of two-phonon-mode behaviour in this material.