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Stable Defects in Semiconductor Nanowires
Nano Letters ( IF 9.6 ) Pub Date : 2018-04-06 00:00:00 , DOI: 10.1021/acs.nanolett.8b00620
A. M. Sanchez 1 , J. A. Gott 1 , H. A. Fonseka 1 , Y. Zhang 2 , H. Liu 2 , R. Beanland 1
Affiliation  

Semiconductor nanowires are commonly described as being defect-free due to their ability to expel mobile defects with long-range strain fields. Here, we describe previously undiscovered topologically protected line defects with null Burgers vector that, unlike dislocations, are stable in nanoscale crystals. We analyze the defects present in semiconductor nanowires in regions of imperfect crystal growth, i.e., at the nanowire tip formed during consumption of the droplet in self-catalyzed vapor–liquid–solid growth and subsequent vapor–solid shell growth. We use a form of the Burgers circuit method that can be applied to multiply twinned material without difficulty. Our observations show that the nanowire microstructure is very different from bulk material, with line defects either (a) trapped by locks or other defects, (b) arranged as dipoles or groups with a zero total Burgers vector, or (c) have a zero Burgers vector. We find two new line defects with a null Burgers vector, formed from the combination of partial dislocations in twinned material. The most common defect is the three-monolayer high twin facet with a zero Burgers vector. Studies of individual nanowires using cathodoluminescence show that optical emission is quenched in defective regions, showing that they act as strong nonradiative recombination centers.

中文翻译:

半导体纳米线中的稳定缺陷

半导体纳米线通常被认为是无缺陷的,这是因为它们能够消除具有长距离应变场的移动缺陷。在这里,我们用空的Burgers向量描述了以前未发现的拓扑保护线缺陷,该缺陷与位错不同,在纳米级晶体中是稳定的。我们分析了不完全晶体生长区域中半导体纳米线中存在的缺陷,即在自催化气-液-固生长以及随后的气-固壳生长过程中液滴消耗过程中形成的纳米线尖端。我们使用一种形式的Burgers电路方法,可以轻松地将孪生材料倍增。我们的观察结果表明,纳米线的微观结构与块状材料有很大不同,其线缺陷可能是(a)被锁住或其他缺陷所困,(b)排列为偶极子或组,其Burgers向量总为零,或(c)零Burgers向量。我们发现了两个新的线缺陷,它们的Burgers向量为零,这是由孪生材料中的部分位错的组合所形成的。最常见的缺陷是零汉堡向量的三层高双晶面。使用阴极发光的单个纳米线的研究表明,光发射在缺陷区域被淬灭,表明它们充当强的非辐射复合中心。
更新日期:2018-04-06
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