SIS结构光电器件的光子辅助量子隧穿效应的研究

The main points of this proposal is to explore the mechanism of the carrier tunneling in the opto-electronic heterojunction device which is irradiated by natural light.Basing on the routine of the charge transfer theory,the fabrication and characterization of advanced optoelectronic films and device physics, the property of AZO film, the structure of graphene oxide(GO)/SiO2 buffer layers， the Ohmic contacts of metals and ZnO, and the carrier tunneling, build-in field and the effective force of AZO/GO/SiO2/Si optoelectronic device have been investigated. The likely enhancement of the stability and the conversion efficiency by introducing GO layer into original SIS device leading to the improvement of opto-electric conversion will be studied in an extensive methodology. The essence of photon-assisted highlight of quantum tunneling at low temperature (<150 K) will be characterized with a specific I-V or C-V measurements. . The electronic states at surface and interface of intermediate region for the physical device will be analyzed through the effecitive spectroscopies. The high density of the point defects from the lattice mismatch, dislocation and adatom within the region resulting in the recombination, the reduction of average free path and minority lifetime of carrier will be investigated. . The tentative dynamic model associated with the experimental data will be applied to the calculation of the probability in which the electron passes through the barrier of the heterojunction at working temperatures. . In the project, a detail scheme both in experimental and theoretical aspects will be put forwarded for the modification, optimization and improvement of SIS device for the high quality of photoelectricity response. Those of pertinent and effictive methods, new principle and novel technique will be yielded to solve the essential academic and technologic problems.

本课题的核心是研究具有特殊结构半导体异质结器件的载流子隧穿机理问题。旨在从电荷转移理论、先进功能薄膜材料制备-表征实验和器件工艺技术三个方面，探索和研究掺铝氧化锌薄膜（AZO）的半导体性质,石墨烯氧化物（GO）/SiO2过渡层的电子结构，金属-ZnO欧姆接触，以及AZO/GO/SiO2/Si光电器件的量子（载流子）隧穿机理和有效力场等动力学问题，探索新材料的引入对改善器件光电转换性能、增强光电转换效率和器件稳定性能的作用。研究低温（<150K）下的量子隧穿现象和光子作用下的量子隧穿增强效应的本质。本课题将采用恰当的动力学模型，计算电子－空穴穿越异质结势垒的概率流密度，分析界面区域和点缺陷高浓度区域的量子平均自由程，少子寿命和界面态密度等因素对器件光电导参数分布的影响，设计具有针对性的实验方法，提出实验上和理论上的解决方案，优化SIS 结构，为光电器件的新原理、新技术探索提供理论和实验依据

本项目历经4年，基于SIS，HIT，Triex-QTSC 和 TOPCon 结构等同类型的光伏器件的潜在的科学技术价值，从新型功能材料、光伏器件结构和量子输运等基础内容入手，提出了立足于源头上的“量子隧穿”和“表面钝化”相平衡、“空间电荷区”与“反型层”相兼容、“氧化物半导体”与“非晶-单晶半导体”相融合等基本思路，采用物化气相沉积技术和薄膜微结构-性能表征实验，结合密度泛函与分子动力学理论计算方法，全面研究了不同晶态与带隙结构半导体材料的匹配、元素掺杂改性、半导体-半导体和半导体-金属的界面性质，分析了光生载流子的输运特征和隧穿概率，成功地完成了以下几个方面的研究内容：1）建立和实施了低温磁控溅射制备TCO（Transparent Conductive Oxide）薄膜材料的方法，不仅成功制备了性能优良的ITO, AZO, IZO, IGO和Er,Tm等稀土掺杂ZnO薄膜材料，而且获得了一次性成型的超薄In-Sn掺杂氧化硅SiOx（In,Sn）功能层材料,使其同时具备了晶硅表面钝化、器件的空穴隧穿、等效p-n结或反型层、空间电荷区、选择性接触和热力学稳定的功能，成为“准SIS结构”光伏器件的核心材料；2）HR-TEM和深度刻蚀XPS分析表明，晶硅表面钝化和量子隧穿是由磁控溅射沉积ITO薄膜的过程中所形成的超薄氧化硅薄膜实现的，该薄层的厚度小于2nm，原子成键网格是非晶型，存在多种Si-O、Si-In、Si-O-In键与化合态,与TCO薄膜和晶硅衬底没有明晰的界面，它的物理、化学性质有待实验确定，具有挑战性；3）但是，它的电子结构由第一性原理和分子动力学计算得到确定，预言了两种电子态能级，可以解释实验结果；4）得到了性能稳定、光电转换参数优良和具有推广意义的光伏器件：光电转换效率达12.2%,填充因子为74.2%，短路电流密度为30.5 mA/cm2，开路电压为0.54V，达到目前世界上该类器件较高的值。.在项目实施过程中，发表期刊论文30篇，会议报告19篇，完成发明专利3项，培养硕、博士10名，青年教师3名。