Sintering densification of ITO targets with low tin oxide content for depositing TCO films as electrodes of solar cells

Abstract

Highly efficient solar cells demand transparent and conductive oxide films with high electronic mobility. Decreasing SnO2 content in In2O3 targets (ITO) is one of important ways, but resulting in difficulty of sintering densification. ITO targets with SnO2 contents of 1 wt%, 2 wt.% and 3 wt% were prepared by microwave sintering. Harmless sintering additives of TiO2 and trances of SiO2 promotes sintering densification. All the targets show the cubic bixbyite phase and dense microstructure. The fine grains with the average size of several microns were obtained. Higher sintering temperature contributes to eliminating the pores in targets, enhancing density and decreasing resistivity. The optimal sintering temperature of 1550 °C obtains the highest relative density (>99 %) and low resistivity (<3.4 × 10−4 Ω cm). The enhanced density of these ITO targets with low SnO2 content can effectively inhibit the formation of nodules on the surface of target during magnetron sputtering.