In this work, the application of RF power in stepped mode during the growth process of CdTe films deposited on glass substrates at room temperature and their structural, morphological, and optical properties were studied. The working pressure and deposition time during deposition were 10 mTorr and 120 min, respectively, meanwhile the RF power was gradually varied from 30 W to 40 W. For comparison and reference, CdTe films with 30 W and 40 W (fixed power values) were also deposited, which resulted amorphous. The x-ray diffraction results of the films prepared with stepped RF power were polycrystalline with cubic structure and (111) as preferential orientation. The crystallite size of films changes from 16.6 to 29.2 nm as the rate of the stepped RF power increases. Raman spectra show that intensity of peaks located at 123, 140 and 164 cm-1 increase with the increased rate of stepped RF power, as well as the rms-roughness and grain size values increase from 0.8 nm to 1.6 nm and from 62.8 nm to 92.1 nm, respectively. The UV-Vis spectra show that the bandgap energy of the deposited CdTe films changes from 1.47 to 1.54 eV with the increased rate of stepped RF power. The obtained bandgap energy values of the CdTe films are adequate to be used as absorber material for photovoltaic applications into the ZnO/CdTe and CdS/CdTe solar cells.

Surface roughness significantly affects light reflection and absorption, which is crucial for light–matter interaction studies and material characterization. This work examines how nanoscale surface roughness affects the electronic states and vibrational properties of cadmium telluride (CdTe) single crystals, using photoluminescence (PL) and resonant Raman scattering (RRS) spectroscopies. We have evaluated the surface roughness across various sample regions as the root-mean-square (RMS) value measured by atomic force microscopy (AFM). At room temperature, increasing RMS correlated with changes in PL intensity and peak width, as well as enhanced second-order longitudinal optical (2LO) phonon mode intensity. Fitting the PL and RRS spectra with Gaussian and Lorentzian functions, respectively, allowed us to explain the relationship between surface morphology and the observed spectral changes. Our findings demonstrate that surface roughness is a critical parameter influencing the surface states and vibrational properties of CdTe, with implications for the performance of CdTe-based devices.