Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Precise Optical Measurement of Carrier Mobilities Using Z-scanning Laser
  Photoreflectance   A simple yet precise optical technique for measuring the ambipolar carrier
mobility in semiconductors is presented. Using tightly focused Gaussian laser
beams in a photo-reflectance system, the modulated reflectance signal is
measured as a function of the Z (longitudinal) displacement of the sample from
focus. The modulated component of the reflected probe beam is a Gaussian beam
with its profile determined by the focal parameters and the complex diffusion
length. The reflected probe beam is collected and input to the detector,
thereby integrating over the radial profile of the beam. This results in
analytic expressions for the Z dependence of the signal in terms of diffusion
length and recombination lifetime. Best fit values for the diffusion length and
recombination lifetime are obtained via an iterative fitting procedure. The
output diffusion lengths and recombination lifetimes and their estimated
uncertainties are combined according to the Einstein relation to yield the
mobility and its uncertainty.

35
The categories of this paper are: mtrl-th
22
The categories of this paper are: chao-dyn
27
The categories of this paper are: comp-gas
6
The categories of this paper are: astro-ph
31
The categories of this paper are: ao-sci
29
The categories of this paper are: funct-an
30
The categories of this paper are: q-alg
2
The categories of this paper are: math
28
The categories of this paper are: alg-geom
20
The categories of this paper are: acc-phys
1
The categories of this paper are: cs
21
The categories of this paper are: adap-org
13
The categories of this paper are: quant-ph
9
The categories of this paper are: nlin
33
The categories of this paper are: plasm-ph
25
The categories of this paper are: patt-sol