| 초록 |
Transparent conductive oxide (TCO) films such as Sn-doped indium oxide (ITO) have been widely applied to transparent electrodes for display devices due to low electrical resistivity and high optical transparency. However, as ITO films have some shortcomings, e.g. difficulty of growth at low temperatures, instability in the hydrogen plasma environment, toxicity, and expensiveness of the source material In, alternative TCO materials have been sought. It has been proposed that Al-doped ZnO (AZO) films would be attractive substitutes for ITO films due to good deposition characteristics at low processing temperatures and high chemical stability under various processing environments while fulfilling basic requirements for transparent electrodes of display devices. In the current study, applicability of AZO films to the transparent electrodes of liquid crystal display (LCD) devices has been investigated by fabricating prototype LCD cell based on twisted nematic liquid crystals (TN-LCs) and AZO films. Al-doped ZnO films were deposited by an rf magnetron co-sputtering at room temperature and modified by post-annealing treatment in hydrogen ambient for better electrical properties. The prototype AZO-based LCD cell showed almost identical optical and electrical characteristics to typical ITO-based LCD cells, demonstrating the applicability of AZO films as electrodes of LCD devices. In addition, when compared with typical ITO-based LCD cells, AZO-based LCD cell showed much reduced residual DC characteristics, which is attributed to the removal of charge trapping centers typically existing in conductive metal oxides, by the post-annealing passivation treatment in hydrogen ambient, further demonstrating AZO advantage. |
