Improved structural and electrical properties of thin ZnO:Al films by dc filtered cathodic arc deposition
- PDF / 250,548 Bytes
- 6 Pages / 584.957 x 782.986 pts Page_size
- 69 Downloads / 180 Views
en J. Mendelsberg Lawrence Berkeley National Laboratory, Plasma Applications Group, Berkeley, California 94720; and Lawrence Berkeley National Laboratory, Molecular Foundry, Berkeley, California 94720
Sunnie H.N. Lim Lawrence Berkeley National Laboratory, Plasma Applications Group, Berkeley, California 94720
Jiaqi Zhu and Jiecai Han Harbin Institute of Technology, Harbin 150080, People’s Republic of China
André Andersb) Lawrence Berkeley National Laboratory, Plasma Applications Group, Berkeley, California 94720 (Received 23 August 2011; accepted 26 September 2011)
Transparent conducting oxide films are usually several 100-nm thick to achieve the required low sheet resistance. In this study, we show that the filtered cathodic arc technique produces high-quality low-cost ZnO:Al material for comparably smaller thicknesses than achieved by magnetron sputtering, making arc deposition a promising choice for applications requiring films less than 100-nm thick. A mean surface roughness less than 1 nm is observed for ZnO:Al films less than 100-nm thick, and 35-nm-thick ZnO:Al films exhibit Hall mobility of 28 cm2/Vs and a low resistivity of 6.5 10 4 Xcm. Resistivity as low as 5.2 10 4 Xcm and mobility as high as 43.5 cm2/Vs are obtained for 135-nm films.
I. INTRODUCTION
Aluminum-doped zinc oxide (ZnO:Al or AZO) is the leading candidate for the replacement of indium tin oxide (ITO) for applications requiring low cost transparent conductors. It is known that the electrical and optical properties of transparent conducting oxide (TCO) thin films, including ITO,1–3 fluorine-doped tin oxide,4–6 gallium-doped zinc oxide,7,8 and AZO,9–11 are strongly dependent on film thickness. ITO is often preferred for its excellent properties, but its cost is high due to increasing demand for displays, solar cells, and smart windows. AZO, in contrast, is produced from abundant, low-cost, and nontoxic materials. One approach to lower cost is reducing film thickness, and indeed ITO films exhibit relatively low resistivity even for film thickness less than 100 nm.12 Further savings could be realized if high quality AZO was available. However, the electrical properties of sputter-deposited AZO thin films deteriorate a)
Address all correspondence to this author. e-mail: [email protected] b) This author was an editor of this focus issue during the review and decision stage. For the JMR policy on review and publication of manuscripts authored by editors, please refer to http://www.mrs. org/jmr-editor-manuscripts/ DOI: 10.1557/jmr.2011.342 J. Mater. Res., Vol. 27, No. 5, Mar 14, 2012
quite dramatically when film thickness is less than 150 nm. Though much effort has been made to obtain high quality AZO films, achieving low resistivity and high mobility AZO films thinner than 100 nm is still a tough challenge. Various methods have been used to prepare AZO thin films, among which magnetron sputtering (MS)13–22 and pulsed laser deposition (PLD)23–28 are common. Less common is filtered cathodic arc deposition (FCAD), but it has been widely used to fabricate hi
Data Loading...
