Effect of oxygen ambient on structural, optical and electrical properties of epitaxial Al-doped ZnO thin films on r-plane sapphire by pulsed laser deposition

摘要

Al-doped ZnO (ZnO:Al) thin films were grown epitaxially on r-plane sapphire substrate by pulsed laser deposition. Substrate temperature of 400 degrees C and pulsed repetition rate of 5 Hz was kept constant during the deposition. The effect of oxygen ambient pressure from 0.1 to 10 mTorr on structural, optical and electrical properties of the ZnO:Al films were investigated. The lowest resistivity was found to be 2.14 x 10(-3) Omega-cm with a carrier concentration of 6.89 x 10(19) cm(-3) for the film deposited in 1 mTorr of oxygen pressure. ZnO:Al film revealed smoother surface obtained at oxygen ambient pressure of 1 mTorr. The epitaxial relationship between ZnO:Al films and r-plane sapphire was found to be (0001)(Zno) / / (01 (1) over bar2)(sapp) and [10 (1) over bar0](Zno) / / [0 (1) over bar 11](sapp). Photoluminescence spectra of the film grown at the oxygen ambient pressure of I mTorr exhibited peak at 3.34 eV, without any deep level.