Temperature dependence study of near-band-edge transitions of compressively strained quaternary GaAsPSb layer by photoreflectance and piezoreflectance spectroscopy

摘要

The optical properties of a strained GaAsPSb layer grown on GaAs substrate by metal-organic vapor-phase epitaxy were characterized by photoreflectance (PR) and piezoreflectance (PzR) techniques. The strain induced splitting of the valence band was observed. Identification of conduction to heavy-hole band and conduction to light-hole band transitions were achieved by comparing the relative intensities of PR and PzR spectra. The results revealed that the GaAsPSb film is under compressive strain. The temperature dependences of near-band-edge transition energies were analyzed using Varshni and Bose-Einstein expressions in the temperature range from 77 to 400 K. The parameters that describe the temperature variations of the near-band-edge transition energies and broadening parameters were evaluated and discussed.