Raman investigation on thin and thick CdTe films obtained by close spaced vacuum sublimation technique

The CdTe thin and thick films were obtained by the close spaced vacuum sublimation technique on a glass substrate under the following growth conditions: the evaporator temperature was 620 °C; and the substrate temperature was varied in the range from 250 °C to 550 °C. High purity CdTe powder was used as a charge for evaporation. The Raman spectra were measured using TRIAX 320 and TRIAX 550 spectrometers at room temperature. The 488‐nm line and 514.5‐nm line of an Ar+ laser and a 785‐nm diode laser were used as excitation sources. The signal was collected by the liquid nitrogen cooled charge‐coupled‐device (CCD) detector. A number of intense Raman peaks at 140, 167, 190, 271, 332 and 493 cm‐1 were observed and were interpreted as TO (140 cm‐1), 1LO (167 cm‐1), 2LO (332 cm‐1), 3LO (493 cm‐1) phonon modes and plasmon‐phonon mode (190 cm‐1). The presence of several phonon replicas in the Raman spectra confirms high crystal quality of the samples. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)