The results of isothermal and nonisothermal crystallization investigations of
the (As₂S₃)₁₀₀-x(SbSI)x (53≤x≤80) thin films are given. It is shown that the films
crystallization is accompanied by a sharp decrease in transmission. The phase structure
arising in the matrix of films during crystallization corresponds to the structure of
crystalline SbSI. The formation mechanism of nanocrystalline SbSI inclusions in the
amorphous matrix is discussed.