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) similar to 10(16) cm(-3) and 440 cm(2)/V s, respectively. Transport characteristics are calculated by solving the Boltzmann transport equation using a variational method. Mobility limit of 430 cm(2)/V s 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 those. In the experimental "mobility versus concentration" curve, unusual phenomenon was observed, i.e., mobilities at n(s) similar to 5 x 10(18) cm(-3) are significantly smaller than those at higher densities above similar to 10(20) cm(-3). It is qualitatively explained in terms of electron-plasmon interaction.
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