Piezo-optical coefficients of ZnSe and ZnTe above the fundamental gap

The piezo-optical coefficients P₁₁-P₁₂ and P₄₄ have been measured for ZnSe and ZnTe above the fundamental gap (in the energy ranges 2.6-5.5 eV and 2.0-5.5 eV, respectively) by using reflectance difference spectroscopy. The measured spectra of P₁₁-P₁₂ and P₄₄ show good Kramers-Kronig consistency between their real and imaginary parts. Values for the deformation potentials D₁⁵, D₃³, and D₃⁵ for the E₁ and E₁+Δ₁ transitions were estimated by fitting the spectral dependence of P₁₁-P₁₂ and P₄₄ to analytical line shapes based on a one-electron approximation.