Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Absence of an intrinsic value for the surface recombination velocity in
  doped semiconductors   A self-consistent expression for the surface recombination velocity $S$ and
the surface Fermi level unpinning energy as a function of light excitation
power ($P$) is presented for n- and p-type semiconductors doped above the
10$^{16}$ cm$^{-3}$ range. Measurements of $S$ on p-type GaAs films using a
novel polarized microluminescence technique are used to illustrate two limiting
cases of the model. For a naturally oxidized surface $S$ is described by a
power law in $P$ whereas for a passivated surface $S^{-1}$ varies
logarithmically with $P$. Furthermore, the variation in $S$ with surface state
density and bulk doping level is found to be the result of Fermi level
unpinning rather than a change in the intrinsic surface recombination velocity.
It is concluded that $S$ depends on $P$ throughout the experimentally
accessible range of excitation powers and therefore that no instrinsic value
can be determined. Previously reported values of $S$ on a range of
semiconducting materials are thus only valid for a specific excitation power.

37
The categories of this paper are: supr-con
18
The categories of this paper are: econ
3
The categories of this paper are: physics
30
The categories of this paper are: q-alg
14
The categories of this paper are: math-ph
15
The categories of this paper are: nucl-ex
20
The categories of this paper are: acc-phys
19
The categories of this paper are: eess
10
The categories of this paper are: q-bio
9
The categories of this paper are: nlin
6
The categories of this paper are: astro-ph
13
The categories of this paper are: quant-ph
26
The categories of this paper are: bayes-an
16
The categories of this paper are: stat
29
The categories of this paper are: funct-an
36
The categories of this paper are: cmp-lg