Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Fabrication of high quality GaN nanopillar arrays by dry and wet
  chemical etching   We study strain relaxation and surface damage of GaN nanopillar arrays
fabricated using inductively coupled plasma (ICP) etching and post etch wet
chemical treatment. We controlled the shape and surface damage of such
nanopillar structures through selection of etching parameters. We compared
different substrate temperatures and different chlorine-based etch chemistries
to fabricate high quality GaN nanopillars. Room temperature photoluminescence
and Raman scattering measurements were carried to study the presence of surface
defect and strain relaxation on these nanostructures, respectively. We found
that wet KOH etching can remove the side wall damages caused by dry plasma
etching, leading to better quality of GaN nanopillars arrays. The Si material
underneath the GaN pillars was removed by KOH wet etching, leaving behind a
fine Si pillar to support the GaN structure. Substantial strain relaxations
were observed in these structures from room temperature Raman spectroscopy
measurements. Room temperature Photoluminescence spectroscopy shows the
presence of whispering gallery modes from these the nano disks structures.

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The categories of this paper are: q-bio
33
The categories of this paper are: plasm-ph
27
The categories of this paper are: comp-gas
36
The categories of this paper are: cmp-lg
16
The categories of this paper are: stat
35
The categories of this paper are: mtrl-th
13
The categories of this paper are: quant-ph
32
The categories of this paper are: atom-ph
7
The categories of this paper are: hep-th
15
The categories of this paper are: nucl-ex
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The categories of this paper are: math
22
The categories of this paper are: chao-dyn
14
The categories of this paper are: math-ph
28
The categories of this paper are: alg-geom
37
The categories of this paper are: supr-con
24
The categories of this paper are: dg-ga