Temperature dependence of electroreflectance spectroscopy in Ga_0.5In_0.5P alloy

Abstract

Electroreflectance (ER) measurements have been carried out to investigate critical point (CP) structures in weakly ordered Ga 0.5 In 0.5 P alloy at temperatures between 11 and 300 K. The measured ER spectra reveal distinct structures at ∼1.9-2.0 eVThese structures are well explained by a three-dimensional [E 0 /(E 0 + 0 )] and a two-dimensional one-electron CP line shape [E 1 /(E 1 + 1 ) and E 2 /(E 2 + δ)]. The temperature dependence of the CP parameters (energy, amplitude and broadening parameter) has been determined and analysed using the Varshni equation and an analytical four-parameter expression developed for the explanation of the band-gap shrinkage effect in semiconductors. The spin-orbit split off energies have also been determined to be 0 ∼ 80 meV and 1 ∼ 256 meV, which are almost temperature independent.