Conductive and transparent V-doped ZnO thin films grown by radio frequency magnetron sputtering

Abstract

Transparent conductive films of vanadium (V)-doped zinc oxide (VZO) were deposited by radio frequency magnetron sputtering on quartz substrates using a ceramic ZnO target with V chips. The electric, optical and structural properties of VZO thin films (V concentration of 0–4at.%) were investigated at various substrate temperatures (TSUB) from 200 to 600°C. The resistivity sharply decreased by V doping, and the resistivity reached a minimum of about 5×10−4Ωcm and 1×10−3Ωcm for TSUB=200°C and 600°C, respectively. It was almost constant up to V concentration of 1.0–1.5% and gradually increased at higher V concentration. The optical transmittance (λ=500nm) of VZO films (V=0.9–1.1%) drastically degraded from about 80% to 40% for TSUB of below 225°C while that of ZnO films was over 83% for TSUB of over 200°C. From the dependence of growth rate and the expansion of c-axis lattice constant in the VZO film, the V configuration was considered to have a charge number of 3.