V掺杂ZnO透明导电薄膜研究

本文分别采用磁控溅射技术与基于密度泛函理论的平面波赝势方法两种方式, 对高价态差元素V掺杂ZnO薄膜进行研究. 实验研究结果表明: V的掺入并未改变ZnO的生长方式, 所制备的薄膜都呈(002)择优生长; 随着衬底温度增加, VZO薄膜的结晶质量逐步改善, 当衬底温度超过280 ℃时薄膜的结晶质量恶化; 在280 ℃时获得的VZO薄膜电阻率最低3.8×10^-3 Ω·m, 500-2000 nm平均透过率高于85%. 理论模拟结果表明: V以替位形式掺入ZnO六角纤锌矿晶格结构中, 费米能级进入导带, 材料表现出n 型半导体的特性, 导电电子主要由V 3d及O 2p电子轨道提供. 理论计算结果与实验结果的一致性, 表明VZO薄膜具有作为高效Si基薄膜太阳电池透明导电薄膜的应用潜力.

Investigation of V doped ZnO transparent conductive oxide films

The performance of the ZnO film that is an indispensable part of pin-type Si-based thin-film solar cells, plays a crucial role in high-efficiency thin-film solar cells and also forms a significant part in photovoltaic research and development. In this paper, low resistivity and wide broadband spectrum transmittance vanadium (V) doped ZnO (VZO) films are successfully fabricated on Corning XG substrates at various substrate temperatures (STs). The properties of VZO films are investigated by the radio-frequency magnetron sputtering technique and plane wave pseudo-potential method based on the density-functional theory. The experimental results demonstrate that all the VZO flms have (002) preferred orientation with the c-axis perpendicular to the substrate, and the crystalline quality is found to increase with the substrate temperature (ST) rising up to 280 ℃ and decrease when the ST increases further. The optimal VZO film is achieved at 280 ℃ with a resistivity of 3.8×10^-3 cm and an average transmittance of more than 85% in a range of 500-2000 nm. The theoretical result shows that after incorporation of V the Fermi level goes through the conduction band, showing a typical n-type metallic characteristic. The carriers originate from the orbits of V 3d and O 2p. The calculated lattice constants and mobility for VZO film are in agreement well with the experimental results. The consistency of the theoretical results with the experimental results shows that the VZO thin film has a great potential application as a front contact in high-efficiency thin film solar cells.