Modeling and characterization of interface state parameters and surface recombination velocity at plasma enhanced chemical vapor deposited SiO2–Si interface

Abstract

The effective surface recombination velocity (Seff) at plasma enhanced chemical vapor deposited (PECVD) SiO2/Si interface as a function of surface band bending under illumination was obtained by combining the photoconductive voltage decay measurements with indium tin oxide gate bias voltage, metal-oxide-semiconductor-capacitance voltage, measurements and theoretical calculations. The capture cross sections for electrons and holes are obtained for the first time for the PECVD SiO2/Si interface state. Theoretical calculations of Seff based on the interface parameters, including interface state density and cross sections for electron and hole, were performed to see the effects of the positive oxide charge density (Qox) on Seff. It is found that roughly a 10 times larger value of Qox compared to the midgap interface state density is required to reduce Seff below 10 cm/s for 5 Ω cm (100) p-type Si. These results prove the potential of PECVD SiO2 for effective passivation of Si surfaces for devices like solar cells.