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

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 (V-oc similar to 0.45 V, J(sc)similar to 28.57 mA/cm(2), FF similar to 71.20%, eta similar to 9.63%). Especially, the average interface state density (D-it) of ITO/n-Si interface drops from (1.29 +/- 0.05) to (1.04 +/- 0.02) x10(11) cm(-2)eV(-1) when the sputtering power increases to 120 W, but the D-it sharply rises at higher sputtering power, which is negatively correlated with V-oc and eta. The effective minority carrier lifetime and O/Si ratio within interfacial layer were characterized by mu-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.