Correlation of the Structural and Optoelectronik Properties of Grain Boundaries in Cu(In,Ga)Se2

黄铜矿作为吸收剂在最先进的薄膜太阳能电池技术中的应用，以及其有趣的缺陷和相行为，是一种令人着迷的材料。晶界在这些多晶器件中起着重要的作用。讨论了它们的电子结构及其在器件中的作用的几种模型。这些材料的特殊相行为也会影响其晶界的性质。迄今为止，由于多晶薄膜中晶粒尺寸小且取向随机，阻碍了对晶界的详细研究。本项目旨在研究具有宏观尺寸晶粒的薄膜的外延生长，为详细研究晶粒边界的结构和光电子特性提供材料。将生长的大晶粒将特别允许对单个晶界和邻近块状材料进行独特的霍尔测量。本文将研究与块状材料相反的晶界发光特性。开尔文探针力显微镜将允许直接研究带弯曲和电子亲和力。这些方法将提供一个详细的晶界电子结构模型，这将与它们的微观结构相关联。个别晶界在器件中的作用也将被研究。最后，这些研究将对晶界的电子结构及其在器件中的作用提供更好的理解。

Chalcopyrites are fascinating materials with regard to their application as absorbers in the most advanced thin film solar cell technology and with regard to their interesting defect and phase behavior. Grain boundaries play an important role in these polycrystalline devices. Several models for their electronic structure and their role in the device are being discussed. The peculiar phase behavior of these Materials will also influence the properties of their grain boundaries. A detailed investigation of grain boundaries has so far been hampered by the small size of the grains and their random orientation in polycrystalline films. This project aims at the epitaxial growths of films with grains of macroscopic size to provide material for the detailed investigation of the structural and optoelectronic properties of the grain boundaries. The large grains that will be grown will specifically allow the distinct Hall measurement of single grain boundaries and of the neighboring bulk material. The luminescence properties of the grain boundaries as opposed to the bulk material will be studied. Kelvin probe force microscopy will allow that direct investigation of band bending and electron affinity. These methods will provide a detailed model of the electronic structure of the grain boundaries, which will be correlated with their microscopic structure. The role of individual grain boundaries in devices will be studied as well. At the end these investigations will provide a much better understanding for the electronic structure of grain boundaries and their role in the device.