搜索

x
中国物理学会期刊

F, Al共掺杂ZnO透明导电薄膜的制备及掺杂机理研究

CSTR: 32037.14.aps.69.20200580

Insight of the doping mechanism of F and Al co-doped ZnO transparent conductive films

CSTR: 32037.14.aps.69.20200580
PDF
HTML
导出引用
  • 本文采用磁控溅射技术, 对F和Al共掺杂ZnO (FAZO)薄膜进行研究, 系统地研究了溅射气压对薄膜结构、形貌、光电等特性的影响. 实验研究结果表明: F, Al共掺入并未改变ZnO的生长方式, 所制备的薄膜都呈(002)择优生长; 随着溅射气压增加, FAZO薄膜的沉积速率降低, 结晶质量恶化, 表面形貌由“弹坑状”逐渐变为“弹坑状”与“颗粒状”并存的形貌特性, 表面粗糙度增加. 在0.5 Pa时制备的FAZO薄膜性能最优, 迁移率40.03 cm2/(V·s), 载流子浓度3.92 × 1020 cm–3, 电阻率最低, 为3.98 × 10–4 Ω·cm, 380—1200 nm平均透过率约90%. 理论模拟结果表明: F和Al的共掺杂兼顾了F, Al单独掺杂的优点, 克服了以往金属元素掺杂仅依靠金属元素轨道提供导电电子的不足, 实现了既增加载流子浓度又减少了掺入原子各轨道间相互作用对载流子散射的影响. 掺入的F 2p电子轨道对O 2p及Zn 4s电子轨道产生排斥, 使它们分别下移, 提供导电电子; 同时掺入的Al的3s和3p电子轨道也为导电电子提供了贡献. F和Al共掺之后载流子浓度提升更加显著, 导电性能增强.

     

    Transparent conductive oxide (TCO) films, as transparent electrodes, are widely used in thin-film solar cells. The performance of TCO film has a significant influence on the conversion efficiency of the film solar cell fabricated byusing it. Although the conductivity can be improved by increasing the carrier concentration, the transmittance in the long wave will be sacrificed. Therefore, the only feasible method is to increase the carrier mobility within a certain carrier concentration range, rather than increase the mobility by reducing carrier concentration. In this paper, the F and Al co-doped ZnO (FAZO) films are deposited on glass substrates (Corning XG) by an RF magnetron sputtering technique with using a small amount of ZnF2 (1 wt.%) and Al2O3 (1 wt.%) dopant. The influences of sputtering pressure on the structure, morphology and photoelectric characteristics of the films are respectively investigated by X-ray diffraction analysis, scanning electron microscope, Hall effect measurement, and ultraviolet–visible–near infrared spectrophotometry. All the thin films show typical wurtzite structure with the c axis preferentially oriented perpendicular to the substrate. With the increase of sputtering pressure, the deposition rate of FAZO film decreases, the crystallization quality is deteriorated, surface topography changes gradually from “crater-like” to co-existent “crater-like” and “granular-like”, and the surface roughness increases. The FAZO film deposited at 0.5 Pa presents the optimal performance with a mobility of 40.03 cm2/V·s, carrier concentration of 3.92 × 1020 cm–3, resistivity of 3.98 × 10–4 Ω·cm, and about 90% average transmittance in a range of 380-1200 nm. The theoretical result shows that the co-doping of F and Al takes the advantages of single F and Al doped ZnO films, and overcomes the shortcoming of metal elements doping, which donates the carriers just from doped metal elements. Furthermore, the co-doping of F and Al not only increases the carriers but also reduces the scatterings caused by the inter-orbital interaction of doped atoms. The doped F 2p electron orbitals repel the O 2p and Zn 4s electron orbitals, making them move down and donate electrons. At the same time, the orbitals of Al 3s and Al 3p also make a contribution to the conductivity. After co-doping of F and Al, both the carrier concentration and conductivity increase significantly.

     

    目录

    /

    返回文章
    返回