The influence of CHx coating on the optical properties of porous silicon

In this work, we report a study on the influence of CHx thickness layer on optical properties of CHx/PS/Si structures. The hydrocarbon groups were deposited by plasma of methane–argon mixture. The properties of these structures are investigated by photoluminescence (PL), reflection and spectral response measurements from where a different behavior depending on CHx layer thickness has been observed. The entire total reflection spectrum is modulated by Fabry–Pérot fringes that are a result of thin film interference. As the CHx layer thickness increases, the amplitude of the interferences decreases and a positive shift of the maximum peak is observed. The PL spectra from CHx/PS samples with two CHx layer thicknesses show more intense luminescence than that observed from PS sample and the existence of an optimum thickness CHx that gives the maximum PL intensity. The spectral response spectra show the presence of an intense peak at 450 nm. Finally, the results point out the importance of CHx coating in optoelectronic applications.