Reflectance modulation in HgTe

Three kinds of modulation techniques, electroreflectance, thermoreflectance and piezo-reflectance are employed to determine energy band parameters in HgTe in the range of photon energy 0.5 to 4 eV. The value of the spin-orbit splitting Δ₀ is determined to be 1.08 ± 0.02 eV from the measurement of electroreflectance with the use of the electrolyte technique and is assigned with the help of electroreflectance measurement on Cd_xHg_1?xTe alloys. In thermoreflectance and piezoreflectance near E₁, various information is obtained, such as broadening parameters, the energy gaps, the location of the transition edge and the ratios of deformation potential constants D₁⁵/D₁¹ = ? 1.4 ± 0.5 and D₃⁵/D₃³= 2.3 ± 0.8 at room temperature.