Optical and electrical properties of magnetron sputtering deposited Cu-Al-O thin films

Abstract

We have successfully prepared CuAlO films on silicon (100) and quartz substrates with copper and aluminum composite target by using radio frequency (RF) magnetron sputtering method. We have related the structural and optical-electrical properties of the films to the sputtering area ratio of Cu/Al for the target (r Cu/Al). The deposition rate of the film and r Cu/Al can be fitted by an exponential function. r Cu/Al plays a critical role in the final phase constitution and the preferred growth orientation of the CuAlOphase, thus affecting the film surface morphology significantly. The film with main phase of CuAlOhas been obtained with r Cu/Al of 45. The films show p-type conductivity. With the increase of r Cu/Al, the electrical resistivity decreases first and afterwards increases again. With r Cu/Al of 45, the optimum electrical resistivity of 80 · cm is obtained, with the optical transmittance being 7279 in the visible region (400760 nm). The corresponding direct band gap and indirect band gap are estimated to be 3.6 eV and 1.7 eV, respectively. © 2012 Yongjian Zhang et al.