Improvement of the performance of ITO/a-SiOx/n-Si device by controllable sputtering power and reducible interface states

Abstract

In order to methodically investigate the influence of sputtering power on interface states and performance of ITO/a-SiOx/n-Si device, the indium-tin oxide film (ITO) with thickness of 80 nm, was deposited on n-type silicon substrate by radio frequency magnetron sputtering. The device photovoltaic (PV) performance and the interface states of ITO/n-Si system were measured by solar simulator measurement system and the light-assisted high frequency capacitance-voltage (C–V) method, respectively. The experimental results demonstrate that the PV parameters of the ITO/a-SiOx/n-Si device achieve optimal values of PV parameters at 120 W (Voc~0.45 V, Jsc~28.57 mA/cm2, FF~71.20%, η~9.63%). Especially, the average interface state density (Dit) of ITO/n-Si interface drops from (1.29 ± 0.05) to (1.04 ± 0.02) × 1011 cm−2eV−1 when the sputtering power increases to 120 W, but the Dit sharply rises at higher sputtering power, which is negatively correlated with Voc and η. The effective minority carrier lifetime and O/Si ratio within interfacial layer were characterized by μ-PCD instrument and X-ray photoelectron spectroscopy, respectively. It is found that the device is well passivated by a-SiOx at 120 W. Moreover, the device performance is well-associated with the interface states and sputtering power.