Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Luminescent N-polar (In,Ga)N/GaN quantum wells grown by plasma-assisted
  molecular beam epitaxy at high temperature   N-polar (In,Ga)N/GaN quantum wells prepared on freestanding GaN substrates by
plasma-assisted molecular beam epitaxy at conventional growth temperatures of
about 650 {\deg}C do not exhibit any detectable luminescence even at 10 K. In
the present work, we investigate (In,Ga)N/GaN quantum wells grown on Ga- and
N-polar GaN substrates at a constant temperature of 730 {\deg}C. This
exceptionally high temperature results in a vanishing In incorporation for the
Ga-polar sample. In contrast, quantum wells with an In content of 20% and
abrupt interfaces are formed on N-polar GaN. Moreover, these quantum wells
exhibit a spatially homogeneous green luminescence band up to room temperature,
but the intensity of this band is observed to strongly quench with temperature.
Temperature-dependent photoluminescence transients show that this thermal
quenching is related to a high density of nonradiative Shockley-Read-Hall
centers with large capture coefficients for electrons and holes.

3
The categories of this paper are: physics
0
The categories of this paper are: hep-ph
28
The categories of this paper are: alg-geom
34
The categories of this paper are: chem-ph
16
The categories of this paper are: stat
13
The categories of this paper are: quant-ph
20
The categories of this paper are: acc-phys
17
The categories of this paper are: q-fin
5
The categories of this paper are: gr-qc
33
The categories of this paper are: plasm-ph
9
The categories of this paper are: nlin
2
The categories of this paper are: math
11
The categories of this paper are: hep-lat
19
The categories of this paper are: eess
6
The categories of this paper are: astro-ph
31
The categories of this paper are: ao-sci