Optical and Electrical Properties of Magnetron Sputtering Deposited Cu–Al–O Thin Films

摘要

We have successfully prepared Cu–Al–O 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 (rCu/Al). The deposition rate of the film andrCu/Alcan be fitted by an exponential function.rCu/Alplays a critical role in the final phase constitution and the preferred growth orientation of the CuAlO2phase, thus affecting the film surface morphology significantly. The film with main phase of CuAlO2has been obtained withrCu/Alof 45%. The films show p-type conductivity. With the increase ofrCu/Al, the electrical resistivity decreases first and afterwards increases again. WithrCu/Alof 45%, the optimum electrical resistivity of 80 Ω·cm is obtained, with the optical transmittance being 72%–79% in the visible region (400–760 nm). The corresponding direct band gap and indirect band gap are estimated to be 3.6 eV and 1.7 eV, respectively.