High-Performance Transparent Conducting Ga-Doped ZnO Films Deposited by RF Magnetron Sputter Deposition

Abstract

Ga-doped zinc oxide (GZO) films were deposited using rf magnetron sputter deposition and a Ga2O3(5 wt %)-doped ZnO ceramic target under various deposition conditions. The effects of each deposition condition on the electrical, structural, and optical properties of the GZO films were investigated to obtain a transparent conducting oxide (TCO) with a high transmittance and a low resistivity for a-Si:H thin-film solar cells. Resistivity showed a strong dependence on working pressure and rf power. The lowest resistivity of 1.9×10-4 Ω·cm was obtained at an rf power density of 2.47 W/cm2. The highest figure of merit for the use of TCO was achieved in the 800-nm-thick GZO film [ρ=2.1×10-4 Ω·cm, average transmittance (400–800 nm) = 92.1%] deposited at 10 mTorr and an rf power density of 1.85 W/cm2. These results indicate that the high-performance TCO fabricated in this work is suitable for use as a transparent electrode layer for thin-film solar cells.