Deposition of high-electron-mobility transparent conducting zinc oxide thin films by DC magnetron sputtering in gas mixture of argon and hydrogen

Abstract

Transparent conducting zinc oxide thin films having high electron-mobility are deposited on glass substrates by DC magnetron sputtering in gas mixture of argon and hydrogen at room temperature. Introducing a little amount of hydrogen gas into sputtering Ar gas can remarkedly improve the electron mobility in ZnO thin films. With gas flow rate ratios of hydrogen to argon range from 7.2 % to 19.2 %, ZnO films with hydrogen (ZnO:H) have stable and low resistivity of 6.6×10-4 Ω.cm. At H2/Ar flow rate ratio 7.2 %, electron Hall mobility in ZnO:H film reaches a maximum value of 61 cm2.V-1.s-1. This value is much higher than the one of 23 cm2.V-1.s-1 in pure ZnO films under the same deposition condition. Morever, electron density of 1.51020 cm-3 in ZnO:H films is also higher than the one of 6×1019 cm-3 in pure ZnO films. XRD and FESEM show that the average crystallinegrain size in ZnO:H films are larger than the one in pure ZnO films. The 600-nm-thick ZnO:H films (substrate included) have average transmission of 83 % in the wide wavelength range of 380-1100 nm and low sheet resistance of 11 /square.