Photoreflectance Studies Of Temperature And Hydrostatic Pressure Dependencies Of Direct Optical Transitions In Bgaas Alloys Grown On Gap

BGaAs layers with boron concentrations of 4.1%, 7.4%, and 12.1% are grown by molecular beam epitaxy on a GaP substrate and studied by optical absorption and photoreflectance (PR) spectroscopy with both temperature and hydrostatic pressure dependence. The direct optical transitions from the bands composing the valence band-namely heavy-hole, light-hole, and spin-orbit split-off-to the conduction band are clearly observed in the PR spectra. For the abovementioned optical transitions, their temperature dependencies are obtained in the range from 20 K to 300 K, and analyzed by Varshni and Bose-Einstein relations. Furthermore, the BGaAs alloys are also studied with hydrostatic pressure up to similar to 18 kbar, revealing pressure coefficients of direct optical transitions. The obtained results are discussed within the framework of the band anticrossing model and chemical trends.