热丝CVD法制备硅基薄膜材料及相关太阳电池模拟研究

发布时间：2018-04-04 16:58

本文选题：硅薄膜　切入点：锗薄膜　出处：《南京航空航天大学》2010年博士论文

【摘要】：硅基薄膜材料禁带宽度可调,光电性能良好,是第三代叠结太阳电池材料的研究热点之一。热丝CVD法制备非晶硅、锗硅等硅基薄膜性能相比于PECVD法制备的同类薄膜已表现出一定的优势。其在硅基薄膜材料及相关的太阳电池制备领域的应用前景越来越受到人们的重视。但作为一种新兴方法,热丝CVD法仍有较多规律和机理性问题未能得到很好总结和解决。本论文主要对热丝CVD法制备硅基薄膜材料的工艺参数对所制备薄膜性能的影响规律进行了研究和分析总结,对与之相关的太阳电池结构进行了模拟分析和优化。系统地研究了热丝温度、源气体的流量比、沉积气压、衬底材料等对本征Si、p-Si和n-Si薄膜的结构、光学及电学性能的影响规律,制备了性能满足电池需要的非晶和微晶等不同结晶性的Si薄膜。在衬底温度200℃条件下在Si(111)单晶衬底上得到了质量近乎单晶的外延本征Si薄膜,并且制得了电阻率最低分别为0.036Ω·cm和0.064Ω·cm的高掺杂p-Si和n-Si薄膜。制备硼掺杂p-Ge薄膜时,发现随着源气体中B_2H_6掺杂比例增加,薄膜结晶性变差,Ge(220)择优取向增强,薄膜导电性提高。随着H_2稀释比提高,薄膜的结晶性变好,但掺杂效果劣化。单晶硅衬底比玻璃衬底有利于薄膜晶化。在衬底温度300℃条件下在单晶Si(100)衬底上制得了Raman峰位于300.3cm~(-1),结晶质量较好的(220)取向的p-Ge薄膜。制备n-Si薄膜时,发现PH_3掺杂比例提高和稀释比降低都会使n-Ge薄膜的导电性劣化。制得了电阻率最低分别为0.024Ω·cm和0.10Ω·cm的高掺杂p-Ge和n-Ge薄膜。对本征SiGe薄膜,随着热丝温度的增加,薄膜的沉积速率几乎线性增加。热丝温度的升高有利于Ge-Si键相对含量的增加,但对薄膜中的H键(Ge-H、Si-H等)相对含量无明显影响。薄膜的禁带宽度随着热丝温度升高先增加后减小,在~24A时最大,为1.39eV。硅烷/锗烷流量比(R_(S/G))的增加使薄膜中Ge-Si、Si-Si的相对含量均增加,但当R_(S/G)1.4后Ge-Si键相对含量下降,Si-Si键相对含量显著增大。随着R_(S/G)的增大,Si-H的含量也有所增加。薄膜的禁带宽度随着R_(S/G)的增加满足关系式E_g=0.19R_(S/G)+1.14。随着稀释比增加,薄膜沉积速率下降,薄膜结晶性变好,薄膜中SiH键相对含量增加,其它H键的相对含量下降,薄膜禁带宽度减小。根据半导体一维器件模型的特性参数方程组解得的太阳电池电流密度、电压及器件的结构和性能参数的关系式,对硅基薄膜太阳电池的结构和各层膜性能对电池性能的影响规律进行了模拟分析。结果表明:对于单结电池,掺杂层的厚度越薄电池性能越好,但不能低于形成稳定空间电荷区所必需的最小厚度;为了得到最优电池效率,i-厚度和p-和n-掺杂浓度均有一合理取值范围,超出该范围电池性能劣化,具体的取值范围因材料而异。对上下子电池均为pin结构的双叠结太阳电池的模拟研究表明:上下子电池禁带宽度匹配对电池性能的优化很重要。不同材料构成的双叠结太阳电池的性能比对应的任一材料构成的相同厚度的单结电池的性能明显提高;同种材料构成上下子电池的叠结太阳电池比厚度相同的单结电池的填充因子、转换效率也略有提高。实验研究也验证了叠结结构有利于提高电池性能的结论。对n~+p~-结构的单结SiC电池和SiC/poly-Si叠结太阳电池的初步模拟分析研究表明,在一定范围内提高p~-层掺杂浓度,有利于减少p~-层的厚度,在电池生产时可以减少沉积时间,提高生产效率,降低成本。
[Abstract]:The silicon - based thin - film material has the advantages of adjustable band width and good photoelectric performance , which is one of the hot spots of the third generation of laminated solar cell materials . Compared with the similar thin film prepared by PECVD method , the silicon - based thin film has certain advantages compared with the similar thin film prepared by the PECVD method .

In this paper , the influence of the process parameters on the properties of thin films prepared by hot filament CVD was studied and summarized , and the solar cell structure related to it was simulated and analyzed .

The structure , optical and electrical properties of intrinsic Si , p - Si and n - Si films were studied systematically . The effects of the structure , optical and electrical properties of Si , p - Si and n - Si films on Si , p - Si and n - Si films were studied systematically .

In the preparation of boron - doped p - Ge films , it was found that the crystallinity of the films increased with the increase of the doping ratio of B _ 2H _ 6 in the source gas . The crystallinity of the films was improved . The crystallinity of the films was improved with the increase of the dilution ratio of H _ 2 .

With the increase of R _ ( S / G ) , the relative content of Ge - Si and Si - Si in the films increased , but the relative content of Si - Si bonds increased with the increase of R _ ( S / G ) .

In order to get the optimum cell efficiency , the i - thickness and the p - and n - doping concentration have a reasonable value range , which is beyond the range of battery performance , and the specific value range varies depending on the material .

The simulation results of double laminated solar cells with pin structure for both upper and lower sub - cells show that the performance of single - junction solar cells with the same thickness is obviously higher than that of single - junction cells with the same thickness . The results show that the stacking structure is beneficial to improve the performance of cells . The experimental study also proves that the stacked structure is beneficial to improve the performance of the battery .

【学位授予单位】：南京航空航天大学
【学位级别】：博士
【学位授予年份】：2010
【分类号】：TM914.42

【引证文献】