Amorphous ITAZO films as advanced coatings for cost-effective silicon based photovoltaic device technology

Abstract

80 nm-nominal thick films of multicomponent oxides based on co-sputtering of ZnO:Al2O3 and In2O3:Sn2O ceramic targets were deposited at 190°C onto polished resistive float zone <100> silicon wafers. Dependence of structural, electrical and optical properties with deposition parameters were determined to evaluate their potential as electrode and antireflection coating for silicon heterojunction solar cells. Results showed thin films with indium metal compositions ranging from 40 to 85 wt% with amorphous nature, smooth surfaces (roughness around 0.5 nm) and mobilities higher than 20 cm2V-1s-1. Average transmittance in visible wavelength range of amorphous compounds was around 85%. Tunable refractive index and optical band gap were obtained depending on cation concentrations. Antireflection capability in 350-1100 nm range was lower than 9% for amorphous thin films, clearly improving the 13% value showed by ZnO:Al2O3 binary oxide. These data would reveal a new class of technologically interesting high performance amorphous materials with suitable properties to be used into silicon-based solar devices.