Deposition of K-doped p type ZnO thin films on (0001) Al2O3 substrates

To study the possibility of group-1 elements asp type dopants, potassium (K) has been used to prepare p-ZnO thin films deposited on (000 1) Al2O3 substrates by radio frequency magnetron sputtering technique. The electrical and structure properties of as-grown films have been mainly investigated using Hall measurement, X-ray diffraction (XRD), atom force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The K-doped ZnO films exhibit p type conductivity, and the best sample is obtained at 500 degrees C substrate temperature and 30% oxygen partial pressure with a hole carrier concentration of 8.92 x 10(17) cm(-3), resistivity of 1.8 Omega cm, and hole mobility of 3.89 cm(2)/V s. One dense and uniform surface is also observed from the K-doped films with an average grain size of 8.3 nm and surface roughness of 98.3 nm. The ratio of Zn, 0 and K atoms in films is 1:1.75:0.06. (c) 2007 Elsevier B. V. All rights reserved.