Correlation of fundamental photoreflectance spectra with surface quality of bulk ZnTe semiconductor grown from Te solution

Large size ZnTe single crystals were grown from Te-solution with the vertical Bridgman method. The fundamental photoreflectance (PR) spectra of bulk ZnTe crystal subjected to a successive sequence of surface treatments, i.e., mechanical and chemical polishing, and passivation, have been measured over the wavelength range 200-600 nm at room temperature (RT) for the first time. The shape, relative intensity and evolution of the distinct E₀, E ₁, E₁+Δ₁ and E₂ transitions during each stage of wafer processing were investigated. It was found that, those distinct transitions vary with varying crystal surface quality. The intensity of the reflectance peaks is large with sharp peak profile when the surface has good crystalline quality. However, E₀ peak can be easily eliminated by a small amount of structural damages on the wafer surface. The dispersion tendency of the E₁ and E₁+Δ₁ peaks suggesting the wafer surface is widespread covered by structural damages. The reflection peaks' intensity were all reduced after passivated with H ₂O₂ solution. E₂ peak intensity is more easily to be reduced during passivation.