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Defects in self-catalysed III-V nanowires
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Gott, James Adam (2020) Defects in self-catalysed III-V nanowires. PhD thesis, University of Warwick.
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Abstract
Semiconductor nanowires are poised to be a candidate for next-generation technology with superior performance and a high integration ability. They have unique physical properties that are enabled by their nano-scale form-factor. Nanowires are commonly described as being defect-free due to their ability to expel mobile defects with long-range strain fields. The droplet consumption step in self-catalysed III{V nanowires can produce material with a high density of line defects, often with null Burgers vector, i.e., no long-range strain field. The presence of such defects can diminish device performance and make them unreliable.
This thesis presents an extensive study made into defects present in semiconductor nanowires. Defect structures are analysed from atomic resolution electron microscope images, and observations show that the nanowire microstructure is very different from bulk material. Nanowires can contain line defects that (a) are 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. The most common defect is the three-monolayer high twin facet with a zero Burgers vector. Cathodoluminescence experiments reveal optical emission is quenched in defective regions, showing that they act as strong non-radiative recombination centers.
Stability of defects is tested by in-situ electron microscopy to analyse defect behaviour in GaAsP nanowires using short annealing cycles. Movement of null Burgers vector defects appears to be consistent with the thermally activated single or double-kink mechanisms of dislocation glide, with velocities that do not exceed 1nms
Item Type: | Thesis (PhD) | ||||
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Subjects: | Q Science > QC Physics T Technology > TK Electrical engineering. Electronics Nuclear engineering |
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Library of Congress Subject Headings (LCSH): | Nanowires, Nanowires -- Defects, Semiconductors, Cathodoluminescence | ||||
Official Date: | July 2020 | ||||
Dates: |
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Institution: | University of Warwick | ||||
Theses Department: | Department of Physics | ||||
Thesis Type: | PhD | ||||
Publication Status: | Unpublished | ||||
Supervisor(s)/Advisor: | Sánchez, Ana M. | ||||
Format of File: | |||||
Extent: | xv, 165 leaves : illustrations | ||||
Language: | eng |
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