Measuring of composition of Cd1−XZnxTe layer by spectral ellipsometry method

The technique for precise control of the composition of in-situ heteroepitaxial layers cadmium-zinc-tellurium (CZT) by the spectral ellipsometry method is proposed. Various features of spectrum of triple compound of CZT are considered. Special attention is paid to the spectrum parts close to the critical points E₀, E₀+Delta₀, E₁ and E₁+Delta₁. The dependence of energy location of fundamental absorption edge E₀ on composition is the most evident. Various methods are tried for the determination of E₀ spectrum location. The simplest model of the dependence of dielectric functions on the composition close to absorption edge is built. The spectra calculation with the usage of the model of dielectric functions allows one to raise the determination accuracy of the composition of CZT appreciably. The verification of the technique is carried out ex-situ on set of samples grown by the method of molecular beam epitaxy (MBE).