【作者】 蔡凤萍；

【导师】 程文娟；

【作者基本信息】 华东师范大学 ， 材料物理与化学， 2010， 硕士

【摘要】 薄膜太阳能电池具有非常明显的低成本优势,TCO薄膜作为薄膜太阳能电池前端电极材料占到电池成本的三分之一,因此开发廉价、性能优异的TCO薄膜对进一步降低薄膜太阳能电池的成本具有非常重要的意义。目前,锡掺杂的氧化铟(ITO)薄膜在TCO薄膜市场中居主要地位,但铟是稀有金属,价格昂贵且有毒,极不利于薄膜太阳能电池的成本控制和环境保护。而铝掺杂的氧化锌薄膜(AZO),由于原料充足、成本低廉、无毒、在氢等离子体中稳定,逐渐成为ITO薄膜的最佳替代者。目前,TCO薄膜已经广泛用于透明导电电极和光电子集成器件,AZO薄膜的实际沉积衬底变的非常复杂。因此,研究不同衬底条件和缓冲层厚度对AZO薄膜的结构和光电学性能的影响对研究薄膜太阳能电池转换介质上的AZO薄膜和进一步扩展AZO薄膜的应用领域非常有意义。本文利用磁控溅射技术,选取在多种不同衬底上沉积AZO薄膜,研究了制备工艺、不同衬底材料、不同厚度的缓冲层对AZO薄膜结构和光电学性能的影响,还对其作为太阳能薄膜电池前电极在绒度方面的要求进行了初步探讨,获得了如下主要结果：(1)采用磁控溅射,研究了在载玻片上不同实验条件对AZO薄膜结构和光电学性能的影响,最终发现在靶与衬底间距5 cm、射频功率225 w、工作气压0.8Pa、衬底温度275℃和降温气压0.8 Pa的条件下,得到了电阻率3.88×10-3Ω·cm,方块电阻为19Ω,且可见光平均透过率达到85%的优质商用级AZO薄膜。(2)结合前面已经获得的最优工艺条件,研究了不同衬底材料(石英,硅片,蓝宝石,氮化镓)对AZO薄膜结构和光电学性能的影响。结果发现：在相同沉积条件下,随着衬底材料的晶格结构、晶格常数和热膨胀系数与ZnO越接近,沉积的AZO薄膜结晶质量就会越好,从而薄膜电阻率和方块电阻也越小,电学性能越优异。其中,在Al2O3／GaN上获得的AZO薄膜质量最好,电阻率低达8.55×10-4Ω·cm。(3)在不同的衬底材料和AZO薄膜之间添加ZnO缓冲层,研究不同缓冲层厚度对各种衬底上生长的AZO薄膜的结构和光电学性能的影响。发现在单晶Si和石英衬底上先沉积150 nm的ZnO缓冲层,再沉积AZO得到的薄膜的结晶质量最好,电阻率最小；而相对于Al2O3／GaN衬底,缓冲层厚度为50 nm时样品的结晶质量最好,电阻率最小(4)对在优化工艺下得到的载玻片衬底上的AZO薄膜进行表面粗化处理,以获得绒面。结果发现经用0.06 mol／L的稀盐酸粗化20s后得到的AZO薄膜具有非常优异的绒面,粗糙度74nm,达到了太阳能薄膜电池前电极的绒度要求。更多还原

【Abstract】 Lowcost is a great advantage of thin film solar cell.The cost of TCO thin film as the front-end electrode material of solar cell accounts for one third of all cost. So it is of great significance to develop cheap and excellent TCO Thin film for reducing the cost of thin film solar cell. At present, the Sn-doped indium oxide thin film occupies the main position, but indium is a kind of metal which is rare, expensive, toxic and not conducive to control cost of thin film solar cell and protect environment. While the Al-doped ZnO thin film which is cheap, non-toxic and stable in hydrogen plasma has become the best alternative to ITO.Currently, TCO thin films have been widely used for transparent conductive electrode and optoelectronic integrated devices, so the substrate on which AZO films actually is deposited becomes very various. Therefore, it is very meaningful to research effects of different substrates and buffer layer thicknesses. In this paper, with depositing AZO films on different substrates using magnetron sputtering, we researched the impact of deposition parameters, different substrates, and buffer layer thicknesses on the structure and properties of the AZO films.Additionally, the roughness of AZO films was preliminarily discussed. The main results obtained are as follows:(1)Using magnetron sputtering method, the deposition parameters for AZO films on glass were optimized. Eventually, when the distance of target and substrate is about 5 cm, power of RF is kept at 225 W, working pressure is around 0.8 Pa, temperature of substrate is 275℃and cooling pressure is 0.8 Pa, high-quality AZO thin film, resistivity of which is 3.88×10-3Ω·cm,sheet resistance of which is 19Ω, and average visible transmittance of which reached 85%,was obtained.(2) Under optimum conditions obtained previously, the structure and properties of the AZO films deposited on different substrates (quartz, silicon, sapphire, gallium nitride) were researched.The results show that the closer the lattice structure and lattice constant of substrate are with ZnO, the better the quality of AZO films is.The resistivity and sheet resistance of which are also smaller, and the electrical properties of which are more excellent. Quality of the AZO thin film deposited on Al2O3/GaN is the best,and resistance as low as 8.55×10-4Ω·cm was obtained. (3)With adding ZnO buffer layer between different substrates and AZO films, the influence of buffer layer thicknesses on the structure and properties of the AZO films was studied. It is found that quality of the AZO films was the best and resistivity of which is the minimum when 150 nm ZnO buffer layer between AZO and Si or quartz substrates was added, while for the Al2O3/GaN substrates, the best thickness for buffer layer is 50 nm.(4) The AZO samples obtained under the optimum process were roughened using dilute hydrochloric acid. The results indicate that roughness of the AZO films was 74 nm after being soaked in 0.06 mol/L dilute hydrochloric acid for 20 s, the surface of which had very excellent haze, which met the requirements of the front-end electrode of solar cell.更多还原