Electroreflectance in the GaAs-GaP Alloys

Abstract

The electroreflectance spectra of a series of GaAs-GaP alloys were measured at room temperature. The electric field was applied by immersing the sample in an electrolyte and by biasing it in the blocking direction. The variation of the $E_0$, $E_1$, ${E_0}^{\prime }$, and $E_2$ peaks with concentration is reported. The change in slope in the variation of $E_1$ at concentrations near 50% reported recently is confirmed. $E_1$ exhibits another interesting anomaly: its spin-orbit splitting remains nearly constant from pure GaAs to Ga${\mathrm{As}}_{0.5}$ ${\mathrm{P}}_{0.5}$ and then decreases rapidly. The ${E_0}^{\prime }$ peak exhibits spin-orbit splitting and hence it is believed due to transitions around a point of k space in the [100] direction. The $E_2$ peak splits because of the lack of inversion symmetry.