Optical parameters and photoluminescence of cadmium-doped epitaxial Pb1−xSnxTe films

Barium fluoride (111) cleaved surfaces have been used with the hot-wall method to grow epitaxial Pb_1−xSn_xTe films from source materials either undoped or doped with 0.1, 0.5, or 1 at. % cadmium and having x=0.2. The absorption in the wavelength range 2–13 μm has been measured together with the spectral dependence of the photoluminescence. The cadmium affects the optical width of the forbidden band and the high-frequency dielectric constant, as well as the photoluminescence intensity. The optical absorption spectra of the doped epitaxial films contain additional absorption bands due to the impurity level in the forbidden band. The position of the impurity level has been determined and the shift in it relative to the bottom of the conduction band as the temperature is reduced. Materials Science Institute, National Academy of Sciences of Ukraine. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 8–11, May, 1996.