Abstract:
A study of the optical properties of the Se–S system has revealed a correlation between the dependences of optical absorption coefficient $\alpha$, effective concentration of charged defects $N_t$, and characteristic energy $E_0$ corresponding to the Urbach optical absorption in the spectral region where the Urbach rule works for the Se–S system on the S concentration. These optical properties are controlled by charged defects. It is shown that concentrations of intrinsic charged defects can be changed by variation in composition of the Se–S system. Reflectance spectra of amorphous solid solutions of the Se–S system are studied within the energy range 1–6 eV. Using the Kramers–Kronig method, spectral dependences of optical constants and derivative optical and dielectric functions are calculated. Variation in the spectra of optical parameters with composition of the Se–S system are explained within a cluster model in which the density of electron states is a function of atomic configurations in clusters, i.e., of the character of a short-range order.
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