Interface study of molybdenum oxide thin films on n- and p-type crystalline silicon surface

In this study, the interface analysis of n- and p-type crystalline silicon with molybdenum oxide (MoO_x) thin film for its application as a carrier selective layer has been presented. Sub-stoichiometric MoO_x thin films were grown on glass and n-Si and p-Si substrates by DC reactive sputtering using molybdenum target in pure Ar + O₂ gas ambient at room temperature for 20 min at 60 W DC power. The optical properties were studied using UV–Vis-NIR spectroscopy and the films showed an optical transmittance > 70% in the visible spectrum with an optical band gap of 3.23 eV. FTIR and XPS studies showed the presence of mixed phases of sub-stoichiometric MoO_x in the deposited film. The interface study was done using the capacitance-voltage (C-V) measurement of Al/MoO_x/Si/Al structure at different frequencies. Density of interface traps was found to be of the order of 10¹² cm⁻³ for both n- and p-Si. The barrier heights of approximately 0.65 eV and 0.52 eV were calculated from current-voltage (I-V) measurements for n- and p-Si, respectively. The I-V results demonstrated a good rectifying characteristics with enhanced barrier height for n-Si as compared to p-Si for its application as interfacial layers in silicon solar cells.