Single-crystalline gallium arsenide (GaAs) grown by various techniques can exhibit hillock defects on the surface when sub-optimal growth conditions are employed. The defects act as nonradiative recombination centers and limit solar cell performance. In this paper, we applied near-field transport imaging to study hillock defects in a GaAs thin film. On the same defects, we also performed near-field cathodoluminescence, standard cathodoluminescence, electron-backscattered diffraction, transmission electron microscopy, and energy-dispersive X-ray spectrometry. We found that the luminescence intensity around the hillock area is two orders of magnitude lower than on the area without hillock defects in the millimeter region, and the excess carrier diffusion length is degraded by at least a factor of five with significant local variation. The optical and transport properties are affected over a significantly larger region than the observed topography and crystallographic and chemical compositions associated with the defect.

中文翻译：

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砷化镓小丘缺陷的载体运输研究

当采用次优生长条件时，通过各种技术生长的单晶砷化镓 (GaAs) 会在表面出现小丘缺陷。这些缺陷充当非辐射复合中心并限制太阳能电池的性能。在本文中，我们应用近场传输成像来研究 GaAs 薄膜中的小丘缺陷。在相同的缺陷上，我们还进行了近场阴极发光、标准阴极发光、电子背散射衍射、透射电子显微镜和能量色散 X 射线光谱分析。我们发现，小丘区域周围的发光强度比毫米区域内没有小丘缺陷的区域低两个数量级，并且过量载流子扩散长度降低了至少五倍，局部变化显着。