Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Electron transport in ZnO thin films   Epitaxial, n-type ZnO films grown by a laser molecular-beam epitaxy method
were investigated by the temperature-dependent Hall-effect technique. The 300-K
carrier concentration and mobility were about $n_s \sim 10^{16}$ cm$^{-3}$ and
440 cm$^{2}$/Vs, respectively. Transport characteristics are calculated by
solving the Boltzmann transport equation using a variational method. Mobility
limit of 430 cm$^{2}$/Vs was calculated at 300 K. The temperature dependence of
the mobility for an undoped film is calculated and agrees favorably well with
experimental data if physical parameters are chosen so as to approach to those.
In the experimental `mobility vs concentration' curve, unusual phenomenon was
observed, i.e., mobilities at $n_s \sim 5\times$ 10$^{18}$ cm$^{-3}$ are
significantly smaller than those at higher densities above $\sim 10^{20}$
cm$^{-3}$. It is qualitatively explained in terms of electron-plasmon
interaction.

18
The categories of this paper are: econ
6
The categories of this paper are: astro-ph
34
The categories of this paper are: chem-ph
17
The categories of this paper are: q-fin
35
The categories of this paper are: mtrl-th
32
The categories of this paper are: atom-ph
7
The categories of this paper are: hep-th
30
The categories of this paper are: q-alg
24
The categories of this paper are: dg-ga
22
The categories of this paper are: chao-dyn
25
The categories of this paper are: patt-sol
27
The categories of this paper are: comp-gas
23
The categories of this paper are: solv-int
26
The categories of this paper are: bayes-an
5
The categories of this paper are: gr-qc
31
The categories of this paper are: ao-sci