Comparative study of aluminium-doped zinc oxide and ruthenium–aluminium co-doped zinc oxide by magnetron co-sputtering

Highly oriented polycrystalline aluminium-doped (Al-doped) and ruthenium–aluminium (Ru–Al) co-doped zinc oxide are prepared on borosilicate glass and polycarbonate (PC) substrates by co-sputtering at room temperature. To investigate the effect of Ru doping, co-sputtering is achieved by varying the sputtering power of Ru target while keeping the sputtering target power of Al-doped zinc oxide unchanged. Atomic force microscopy (AFM) data shows that the root-mean-square roughness of all the films is less than ∼ 2.5 nm. With Ru doping, the resistivity of the film improves by one order of magnitude as compared to pure Al-doped zinc oxide sample. The resistivity and carrier concentration values obtained correlated to the degree of crystallinity in the samples. High optical transmittance in the visible range are achieved (> 90% for borosilicate glass and > 80% for PC).