Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Nature of excitons bound to inversion domain boundaries: Origin of the
  3.45-eV luminescence lines in spontaneously formed GaN nanowires on Si(111)   We investigate the 3.45-eV luminescence band of spontaneously formed GaN
nanowires on Si(111) by photoluminescence and cathodoluminescence spectroscopy.
This band is found to be particularly prominent for samples synthesized at
comparatively low temperatures. At the same time, these samples exhibit a
peculiar morphology, namely, isolated long nanowires are interspersed within a
dense matrix of short ones. Cathodoluminescence intensity maps reveal the
3.45-eV band to originate primarily from the long nanowires. Transmission
electron microscopy shows that these long nanowires are either Ga polar and are
joined by an inversion domain boundary with their short N-polar neighbors, or
exhibit a Ga-polar core surrounded by a N-polar shell with a tubular inversion
domain boundary at the core/shell interface. For samples grown at high
temperatures, which exhibit a uniform nanowire morphology, the 3.45-eV band is
also found to originate from particular nanowires in the ensemble and thus
presumably from inversion domain boundaries stemming from the coexistence of N-
and Ga-polar nanowires. For several of the investigated samples, the 3.45-eV
band splits into a doublet. We demonstrate that the higher-energy component of
this doublet arises from the recombination of two-dimensional excitons free to
move in the plane of the inversion domain boundary. In contrast, the
lower-energy component of the doublet originates from excitons localized in the
plane of the inversion domain boundary. We propose that this in-plane
localization is due to shallow donors in the vicinity of the inversion domain
boundaries.

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The categories of this paper are: hep-lat
29
The categories of this paper are: funct-an
12
The categories of this paper are: nucl-th
30
The categories of this paper are: q-alg
16
The categories of this paper are: stat
7
The categories of this paper are: hep-th
24
The categories of this paper are: dg-ga
20
The categories of this paper are: acc-phys
22
The categories of this paper are: chao-dyn
0
The categories of this paper are: hep-ph
33
The categories of this paper are: plasm-ph
13
The categories of this paper are: quant-ph
5
The categories of this paper are: gr-qc
34
The categories of this paper are: chem-ph
3
The categories of this paper are: physics
10
The categories of this paper are: q-bio