Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Photoluminescence study of interband transitions in few-layer,
  pseudomorphic, and strain-unbalanced Ge/GeSi multiple quantum wells   In this paper we investigate the structural and optical properties of few
strain-unbalanced multiple Ge/GeSi quantum wells pseudomorphically grown on
GeSi reverse-graded substrates. The obtained high epitaxial quality
demonstrates that strain symmetrization is not a mandatory requirement for few
quantum-well repetitions. Photoluminescence data, supported by a thorough
theoretical modeling, allow us to unambiguously disentangle the spectral
features of the quantum wells from those originating in the virtual substrate
and to evaluate the impact on the optical properties of key parameters, such as
quantum confinement, layer compositions, excess carrier density, and lattice
strain. This detailed understanding of the radiative recombination processes is
of paramount importance for the development of Ge/GeSi-based optical devices.

3
The categories of this paper are: physics
12
The categories of this paper are: nucl-th
8
The categories of this paper are: hep-ex
28
The categories of this paper are: alg-geom
31
The categories of this paper are: ao-sci
11
The categories of this paper are: hep-lat
0
The categories of this paper are: hep-ph
27
The categories of this paper are: comp-gas
10
The categories of this paper are: q-bio
34
The categories of this paper are: chem-ph
6
The categories of this paper are: astro-ph
18
The categories of this paper are: econ
30
The categories of this paper are: q-alg
20
The categories of this paper are: acc-phys
33
The categories of this paper are: plasm-ph
2
The categories of this paper are: math