Impact of composition on microstructural, electrical and optical properties of ZnO thin films incorporation by In2O3 for solar cells

We report in deposition of highly transparent and conductive thin layers of ZnO-In2O3 by the electron beam gun. The effects of the composition of (ZnO)((1 - x))(In2O3)(x) (x = 0, 2, 4, 6, 8, 10 at%) films on the structure and physical properties were investigated. The films were strongly oriented along the (002) plane. The X-ray diffraction analysis showed that as the In2O3 content increases to 6% of the doping level, the grain size increases and the lattice decreases, and then reverse occurs at 8% to 10% of In2O3 content. The surface of the ZnO-In2O3 thin films was examined by the atomic force microscopy. By constructing a three-layer model to analyze the spectroscopic ellipsometry experimental data, the optical parameters and energy gap were extracted. As the In2O3 content increased, the energy gap decreased from 3.37 to 3.312 at the expense of ZnO. The electrical characteristics of the (ZnO)((1 - x))(In2O3)(x) films were measured using the four-point probe method. We show that the resistivity and sheet resistance of (ZnO)((1 - x))(In2O3)(x) decrease with increasing the In2O3 concentration. The resistivity was found to attain minimum value of 4.5 x 0(-4) omega cm and sheet resistance of 45 omega/sq at 6% of the In2O3 content. The carrier concentration and the carrier mobility increase with In2O up to 6% of the doping level of In2O3 and then decreases. The presented physical properties of the grown (ZnO)(0.94()(In2O3)(0.06) films recommend it for optoelectronic and solar cell applications.

Automated summary

In this study, highly transparent and conductive thin layers of ZnO-In2O3 were deposited using an electron beam gun. The effects of film composition on structure and physical properties were investigated. It was found that increasing the In2O3 content can decrease the energy gap, reduce resistivity and sheet resistance, and increase carrier concentration and carrier mobility.