Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Excitons, biexcitons and trions in self-assembled (In,Ga)As/GaAs quantum
  dots: Recombination energies, polarization and radiative lifetimes versus dot
  height   We calculate the height dependence of recombination energies, polarization
and radiative lifetimes of the optical transitions of various excitonic
complexes: neutral excitons (X^0), negatively- (X^-) and positively-charged
(X^+) trions, and biexcitons (XX^0) in lens-shaped, self-assembled
In_0.6Ga_0.4As/GaAs quantum dots. By using an atomistic pseudopotential method
combined with the configuration-interaction method, we predict the following.
(i) The recombination energy of the lowest transition of X^- blue-shifts as
height increases, whereas that of X^+ red-shifts. Remarkably, the recombination
of XX^0 shows a red-shift at small heights, reaches a maximum shift, and then
blue-shifts for taller dots. (ii) Changes in dot height lead to a
bound-to-unbound crossover for X^-, X^+ and XX^0. (iii) When considering the
[110] and [1\bar{1}0] directions, the lowest transitions of X^0 and XX^0
manifest [110] vs [1\bar{1}0] in-plane polarization anisotropy that switches
sign as a function of height as well as alloy randomness. $X^-$ and $X^+$ show
transitions with negligible polarization anisotropy regardless of height. (iv)
The ground state of X^0 is split in a low-energy pair that is forbidden (dark)
and a high-energy pair that is allowed; thus, at T=0K the radiative lifetime
\tau(X^0) is long (~ ms) due to the dark exciton. On the other hand, at T=10K,
\tau(X^0) decreases moderately as height increases and its magnitude ranges
from 2-3ns. The ground state of X^- and X^+, and that of XX^0 is allowed
(bright); so, \tau(X^-), \tau(X^+) and \tau(XX^0) are fast (~ ns) even at T=0K.
These radiative lifetimes depend weakly on height. In addition, \tau(X^-) ~
\tau(X^+) ~1.1ns, while \tau(XX^0)~0.5ns$. We compare our predictions with
available spectroscopic data.

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The categories of this paper are: stat
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The categories of this paper are: supr-con
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The categories of this paper are: plasm-ph
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The categories of this paper are: hep-th
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The categories of this paper are: hep-ex
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The categories of this paper are: physics
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The categories of this paper are: cs
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The categories of this paper are: math
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The categories of this paper are: alg-geom
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The categories of this paper are: funct-an
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The categories of this paper are: patt-sol
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The categories of this paper are: nucl-ex
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The categories of this paper are: hep-lat
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The categories of this paper are: solv-int