| 학회 | 한국재료학회 |
| 학술대회 | 2008년 가을 (11/07 ~ 11/07, 차세대융합기술연구원) |
| 권호 | 14권 2호 |
| 발표분야 | 전자재료 |
| 제목 | Improving the surface morphologucal and electrical properties of low-pressure sputtered ITO films |
| 초록 | Indium tin oxide (ITO) thin films are highly degenerate wide band gap semiconductors (Eg: 3.4 ~ 4.3 eV). They have a low electrical resistivity due to their high carrier concentration and the location of the Fermi level (EF) above the lower edge of the conduction band (EC). ITO films also exhibit a high level of transmission in the visible-near infrared regions of the electromagnetic spectrum. Due to these unique properties, ITO thin films have been widely studied for their potential use in the opto-electronic industry and newly emerging display devices. So far, several methods have been employed to prepare ITO thin films such as spray pyrolysis, reactive evaporation, pulsed laser deposition, conventional magnetron sputtering, cesium ion induced magnetron sputtering, and ion beam assisted sputtering. Among these deposition methods, magnetron sputtering is preferable, because it allows easy process control for the device structure and the production of display devices with a large area. However, one of the practical drawbacks of sputtered ITO thin films is their rough surface morphology. It is incompatible with their use as the semiconducting layer or transparent electrode of display devices. These functional properties of ITO thin films are strongly dependent on the microstructure resulting from the deposition method and processing conditions. In this study, ITO thin films with smooth surface morphology were obtained using the ultra low-pressure dc magnetron sputtering method (ULPS, where the sputtering pressure is lower than 1 mTorr). It was found that the working pressure largely affects the surface roughness of the films. By comparing the films deposited by the ULPS method with those obtained by the conventional sputtering method at 5 mTorr, it turned out that the surface roughness of the former was 5 times lower. It also resulted in high transparency in the visible range. However, their electrical properties for electrode applications were not suitable. In order to obtain the films with low resistivity and smooth surface morphology, we used the two-step growth method. We achieved low resistivity ITO thin films (3.7×10-4 Ω.cm) using a continuous two-step deposition process, in which the initial layer was deposited at 0.5 mTorr and then the final layer deposited at 5 mTorr, without any additional processes. ULPS was found to be an effective way of enhancing the surface morphology of ITO thin films, which is suitable to be employed in newly emerging display devices. |
| 저자 | 허명수, 양봉섭, 원석준, 김형준 |
| 소속 | 서울대 |
| 키워드 | ITO; ULPS; XPS |
