Inter-Valence-Band Transitions in Uniaxially Stressed Ge and GaAs

The spectra of direct transitions between the heavy-hole band and the spin-orbit-split band in strained Ge and GaAs have been studied. The interpretation involves an approximate k·p treatment in which the strong interaction between the conduction band, the light-hole band, and the spin-orbit-split band was taken into account. There is satisfactory agreement between our experiments on $p$-type Ge and cyclotron-resonance data. Our studies of $p$-type GaAs provide information on the warping of the hole surfaces and the ratio of light-hole to heavy-hole masses. The results were $\frac{B}{A}=0.69\mathrm{}\pm 0.015$ and $\frac{N}{3A}=0.86\mathrm{}\pm 0.01$ for GaAs at room temperature. In both materials there was evidence of considerable freeze-out of holes at temperatures less than 100°K. Our results for the valence-band deformation potentials agree with previous piezo-optical experiments.