透明导电氧化物薄膜材料研究进展

Recent Progress in Study of Transparent Conducting Oxide Films

透明导电氧化物薄膜被广泛应用于太阳能电池、平板显示器以及透明视窗等制备中,成为不可或缺的一类薄膜。综述透明导电氧化物薄膜的发展现状和发展趋势,阐述透明导电氧化物薄膜的导电机理和载流子散射机制,系统概括出材料体系选择原则。化学计量比的氧化物是不导电的,通过在薄膜中引入缺陷,包括氧空位、间隙原子或者外来杂质等,在禁带中形成缺陷能级,从而改变氧化物薄膜的导电性能,形成透明导电氧化物。根据掺杂离子的不同,即受主掺杂离子和施主掺杂离子,透明导电氧化物包括N型和P型半导体两种。在这种由于缺陷的引入而导电的透明氧化物薄膜中,载流子散射主要包括晶界散射、声子散射、杂质离子散射和孪晶界散射四种,其中晶界散射和杂质离子散射占主导。进一步地,重点介绍In2O3、SnO2和ZnO基掺杂透明导电氧化物薄膜的基本性能及应用。In2O3基透明导电氧化物由于其在制备低电阻率薄膜和半导体加工方面的优势,成为制作透明电极的主要材料,而SnO2和ZnO基透明导电氧化物由于成本低廉,在未来替代In2O3基透明导电氧化物在透明电极制备方面具有巨大的潜力。此外,结合多功能电子器件的发展,提出延展性能好的氧化物/金属/氧化物三明治结构的透明导电氧化物薄膜是将来的发展方向和研究重点。

Transparent conducting oxide films（ TCOs）,as indispensable components,have a significant number of application in solar energy batteries,flat panel displays and transparent windows,etc. This paper reviews present status and future prospects for the development of TCOs comprehensively,introduces the conducting and electron scattering mechanisms in TCOs and summarizes the material＇s selection rules for design of TCOs. Basically,the stoichiometric oxide film is non-conductive. However,this non-conductive oxide film can be transformed into conductive film by introducing some defects into the oxide film,e. g. oxygen vacancies,interstitials and exotic dopants,which form an energy level in these oxide films. According to the difference in type of defects,i. e.,acceptor or donor,the transparent conductive oxide film can be classified into N-type and P-type semiconductors. Furthermore,in these defects induced conductive films,there are four scattering mechanisms including boundary scattering,phonon scattering,dopant scattering and twin boundary scattering. Amongst the aforementioned scattering mechanism,boundary scattering and dopant scattering are the two dominant scattering mechanisms in transparent conductive oxide films. Additionally,the properties and applications of impurity-doped In2O3-,SnO2-and Zn O-based TCOs are elaborated in detail. Owing to the advantage in preparation of low resistivity film and processing in semiconducting technology,the In2O3-based TCO is the most used material in preparation of transparent electrode,while the Sn O2-and ZnO based TCOs are the two most significant candidates for substitution of In2O3-based TCO because of their low cost. At last,combined with the development of multifunctional electronic devices,we propose that the transparent conducting film with oxide / metal / oxide sandwich structure is the future direction for improving the conductivity and transparency of TCOs.