Synergetic Effect of Gas Compositions on Material Properties of n-Type Nanocrystalline Silicon Oxide Prepared by Plasma-Enhanced Chemical Vapor Deposition

Hydrogenated nanocrystalline silicon oxide (nc-SiOx:H) has drawn extensive attention during the past years for the utilization of silicon heterojunction (SHJ) solar cells. This material is demonstrated to be the key to the performance improvement of SHJ solar cells. Herein, the influence of the process gas compositions on the optical, electronic, chemical, and structural properties of n-type nc-SiOx:H films at the thickness of 38 nm is systematically investigated. The synergetic effect of CO2 and PH3 gas flow fraction (fCO2$f_{\left(\text{CO}\right)_{2}}$ and fPH3$f_{\left(\text{PH}\right)_{3}}$) and the synergetic effect of CO2 and SiH4 gas flow fraction (fCO2$f_{\left(\text{CO}\right)_{2}}$ and fSiH4$f_{\left(\text{SiH}\right)_{4}}$) on the growth of nc-SiOx:H (n) films are demonstrated. Creatively combining the Fourier-transform infrared, UV-Raman scattering spectroscopy, spectroscopy ellipsometry, and photo-thermal deflection spectroscopy measurement, the mechanism behind the synergetic effect of the gas compositions on the material properties is analyzed. It was demonstrated that the utilization of PH3 or SiH4 would weaken the oxygen incorporation in the hydrogenated nanocrystalline silicon oxide (nc-SiOX:H) films moderately and promote the transition of amorphous silicon oxide (a-SiOX:H) phases to amorphous silicon (a-Si:H) or nanocrystalline silicon (nc-Si:H) phases, which become more obvious at larger CO2 gas flow fraction (fCO2).image (c) 2024 WILEY-VCH GmbH