Study of the structure of $a$-As$_2$Se$_3\langle$Bi$\rangle_x$ amorphous layers by dielectric spectroscopy

Dielectric polarization in amorphous arsenic triselenide layers with various bismuth impurity contents in ac electric fields is studied. The experimental results obtained are interpreted within the model according to which Bi atoms at low concentrations are incorporated into the initial matrix network of the amorphous structure as charged centers; a further increase in the dopant content is accompanied by the appearance of ordered Bi$_2$Se$_3$ inclusions (clusters) in the compositions under study.