晶体硅太阳电池Hf基高κ介电薄膜表面界面钝化研究

Carrier recombination losses on the wafer surface is one of key factors that restrict the efficiency of Si solar cells. The current trend in Si solar cells is towards thinner c-Si wafers, the relative surface area of the cell increases due to the thickness reduction of the wafers, and the surface recombination of the carriers increase significantly. High-quality surface passivation can effectively reduce the surface recombination losses and enhance the efficiencies. Therefore, it is an important issue to find the suitable dielectric films as the passivation layers to improve the efficiency of Si solar cells. This project intends to develop La doped Hf-based high-κ dielectric thin films as the passivation layers of Si solar cells, and the mainly researching contents are showed as below: to prepare Hf-based high-κ dielectric thin films with different La doping concentrations by atomic layer deposition, and check the chemical composition and interface surface structure; to adjust the fixed charge within the high-κ dielectric thin films, investigate the effect mechanism of the fixed charge and the interfacial structure on the passivation performance of the prepared films, and explain the function of La doping; to prepare Si solar cells with La doped Hf-based high-κ dielectric thin films as the passivation layers, study the effect of the La doped Hf-based high-κ dielectric thin passivation layers on the efficiency of Si solar cells, and clarify the passivation mechanism of the La doped Hf based high-k dielectric film on the surface of Si solar cells. Through this research project, it can provide an important scientific basis for the development of the surface passivation techniques for Si solar cells.

载流子在硅表面的复合损失是制约晶体硅太阳电池效率的关键因素之一。目前，晶体硅太阳电池所使用的硅片越来越薄，而薄片化使得电池的相对表面积增大，电池中载流子的表面复合更加凸显。优异的表面钝化能够显著的降低载流子的复合速率。因此，寻找合适的介电薄膜作为钝化层以提高电池效率成为极重要研究课题。本项目拟采用La掺杂Hf基高κ介电薄膜钝化晶体硅太阳电池，研究如下内容：通过原子层沉积技术制备不同La掺杂浓度的Hf基高κ介电薄膜，明确其化学组成和表面界面结构；调控La掺杂Hf基高κ介电薄膜内存在的固定电荷，研究薄膜表面界面结构和固定电荷对其钝化性能的影响机制，解释La掺杂的作用；制备La掺杂Hf基高κ介电薄膜钝化的晶体硅太阳电池，探讨La掺杂Hf基高κ介电薄膜钝化层对电池效率的影响，阐明La掺杂Hf基高κ介电薄膜在电池表面的钝化机理。本项目的研究将为晶体硅太阳电池表面钝化技术的发展提供重要的科学依据。

晶体硅太阳电池具有稳定的性能和成熟的制备工艺，在商用电池中扮演着吃重的角色，但依旧面临着转化效率低、生产成本高等问题。载流子在硅表面的复合损失是制约晶体硅太阳电池效率的关键因素之一。目前，晶体硅太阳电池所使用的硅片越来越薄，而薄片化使得电池的相对表面积增大，电池中载流子的表面复合更加凸显。优异的表面钝化能够显著的降低载流子的复合速率。本项目在前期研究的基础上，深入研究了La掺杂Hf基高κ介电薄膜对晶体硅太阳电池的表面钝化，基本完成预定目标。主要研究了一系列La掺杂Hf基高κ介电薄膜的制备；ALD沉积的一系列高κ介电薄膜的化学组成和界面结构分析；退火温度、退火时间和退火氛围等条件对沉积薄膜表面界面结构的影响；薄膜表面界面结构和固定电荷对薄膜钝化性能的影响；La掺杂Hf基高κ介电薄膜的钝化机理等。以上研究结果对未来晶体硅太阳电池表面钝化技术的发展具有借鉴意义。此外，我们设计了一种采用有双势阱带隙的ZrxSi1-xO2作为俘获层的存储电容器，研究发现双势阱带隙是一种很有前途的非易失性存储器能带结构。. 在项目执行期间，我们共发表标注本项目基金号的SCI论文5篇，申请国家发明专利3项，授权国家实用新型专利1项，四位参与人获得职称晋升。