Dependence of the spectra of charge carriers on the concentration of defects in silver telluride

A change in the band gap as a function of the concentration of electrically active defects in silver telluride has been considered. It has been found that the electronegative and electropositive defects lead to an increase and a decrease in the band gap \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$\varepsilon _{g_0 } $\end{document}, respectively. It has been revealed that, in Ag2Te with Te concentrations of higher than or equal to 0.75 at %, the band gap \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$\varepsilon _{g_0 } $\end{document} has an unusually low value (∼0.008 eV). In the case where the band gap is characterized by the temperature dependence ɛg = (0.008−7 × 10−5T) eV, at T > 100 K, there is a gapless state. Owing to the changes in the concentration of electrically active defects, silver telluride can exhibit n- and p-type conductivities, unlike other silver chalcogenides (Ag2S and Ag2Se).