1,961 research outputs found
Magnetic field induced band depopulation in intrinsic InSb: A revisit
The effect of Landau level formation on the population of intrinsic electrons
in InSb is probed near room temperature in magnetic fields upto 16 Tesla.
Although the measured magnetic field dependence of the Hall coefficient is
qualitatively similar to published results, it is shown that the data may also
be explained by simply including ambipolar conduction. Thus the inference on
band depopulation drawn from previous measurements on InSb is inconclusive
unless both the Hall and the magnetoresistive components of the resistivity
tensor are simultaneously measured and modelled. When the model includes both
depopulation and ambipolar conduction, a reasonable agreement with theory can
be established.Comment: 5 figs, to appear in Journal of Physics : Condensed Matte
Scattering of Carriers by Charged Dislocations in Semiconductors
The scattering of carriers by charged dislocations in semiconductors is
studied within the framework of the linearized Boltzmann transport theory with
an emphasis on examining consequences of the extreme anisotropy of the
scattering potential. A new closed-form approximate expression for the carrier
mobility valid for all temperatures is proposed. The ratios of quantum and
transport scattering times are evaluated after averaging over the anisotropy in
the relaxation time. The value of the Hall scattering factor computed for
charged dislocation scattering indicates that there may be a factor of two
error in the experimental mobility estimates using the Hall data. An expression
for the resistivity tensor when the dislocations are tilted with respect to the
plane of transport is derived. Finally an expression for the isotropic
relaxation time is derived when the dislocations are located within the sample
with a uniform angular distribution.Comment: 3 figure
A parallel and adaptive multigrid solver for the solutions of the optimal control of geometric evolution laws in two and three dimensions
We present a problem concerning the optimal control of geometric evolution laws. This is a minimisation problem that aims to find a control η which minimises the objective functional J subject to some imposed constraints. We apply this methodology to an application of whole cell tracking. Given two sets of data of cell morphologies, we may solve the optimal control problem to dynamically reconstruct the cell movements between the time frame of these two sets of data. This problem is solved in two and three space dimensions, using a state-of-the-art numerical method, namely multigrid, with adaptivity and parallelism
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