Nanoscale Surface Roughness Effects on Photoluminescence and Resonant Raman Scattering of Cadmium Telluride

Featured Application Photoluminescence and resonant Raman scattering have the potential to characterize surface roughness. These optical spectroscopies can be complementary tools for monitoring and controlling semiconductor manufacturing processes.Abstract 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.