Ana M Sanchez and Richard Beanland (Condensed matter)

Semiconductor nanowires are commonly described as being defect-free due to their ability to expel mobile defects with long-range strain fields. Here, we analyse 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-catalysed vapour-liquid-solid growth and subsequent vapour-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 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 zero total Burgers vector or c) having zero Burgers vector. We find two new line defects with 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 zero Burgers vector. Studies of individual nanowires using cathodoluminescence shows that optical emission is quenched in defective regions, showing that they act as strong non-radiative recombination centres.

• Publication: Nano Lett., 2018, 18 (5), pp 3081–3087
• DOI: 10.1021/acs.nanolett.8b00620