Simple approximation for absorption coefficient in degenerate HgCdTe

In this work we propose a simple empirical rule for the absorption coefficient of mercury cadmium telluride (MCT), valid both in the non-degenerate and in the degenerate case. The rule takes into account the Urbach band tailing and non-parabolicity of bands. Additionally, an expression is proposed for the Moss-Burstein effective bandgap spreading in degenerate narrow-band semiconductors. The results are compared to the available experimental data on MCT and to the results of numerical calculation obtained by the Kane model. A critical comparison is made between the proposed rules and the standard approximations used to describe the MCT absorption coefficient.