Effects of sputtering gas pressure and substrate temperature on opitcal properties of ZnO:Al thin films fabricated by RF magnetron sputtering

RF magnetron sputtering gas pressure and substrate temperature on Al-doped ZnO (ZAO) thin film optical performance has important implications. Al-doped ZnO (ZAO) thin films were prepared by RF magnetron sputtering technology. We realized ZAO films with the better performance by adjusting and optimizing the sputtering gas pressure and substrate temperature. Using UV-vis spectrophotometer tested the ZAO film optical performance, which indicates that the samples prepared at 5∼10 Pa sputtering gas pressure have the visible light transmittance above 85 %, but transmittance of the prepared samples at sputtering gas pressure of 1∼4 Pa is below 80 %. The average transmittance of the samples prepared at 250 and 350, 400 °C substrate temperatures did not change obviously and were more than 85%. However, with the further increase of substrate temperature, the transmittance began to fall. Especially, the transmittance of the samples prepared at 500°C decrease below 75%. Using XRD, AFM and four probe tester tests the crystallization, microstructure and electrical properties of ZAO film. The experimental result indicates that the sample prepared at 5 Pa sputtering gas pressure and substrate temperature of 400°C displays excellent optical and electrical properties.