Non-ohmic Transport Research Articles

Low-Temperature Non-Ohmic Galvanomagnetic Effects in Degeneraten-Type InAs

The dependence of the mobility of $n$-InAs on temperature and electric field was measured between 4.2 and 30 K and 0.05 and 10 V/cm, respectively. Furthermore, the variation of the nonoscillatory as well as the oscillatory part of the magnetoresistance (Shubnikov-de Haas effect) with applied electric field was studied experimentally. It was found that the decrease of the amplitudes of the Shubnikov-de Haas (SdH) effect depends on the time after application of the electric field and allows a direct time-resolved observation of the increasing electron temperature. The non-Ohmic transport is interpreted with the aid of an electron-temperature model. At electric fields below 0.3 V/cm, where the electron gas is strongly degenerate, electron temperatures are deduced from the decreases of the SdH amplitudes. At higher fields the degeneracy decreases gradually and electron temperatures are obtained from a comparison of the field-dependent non-Ohmic mobility and the temperature-dependent Ohmic mobility. From energy-balance considerations, the dependences of the electron temperature and the mobility on the electric field strength are calculated up to 10 V/cm assuming that ionized-impurity scattering is the dominant mechanism for momentum relaxation. The energy loss was assumed to involve scattering by acoustic phonons via the screened deformation potential and the screened piezoelectric interaction, and also scattering by polar optical phonons. A value of 4.05 eV for the deformation potential constant yielded good agreement between the experimental and the calculated dependence of the energy-loss rate on the electron temperature up to 18 K. Above 18 K the energy loss because of polar optical phonons, which is \ifmmode \mbox{\c{c}}\else \c{c}\fi{}alculated for a degenerate electron gas, dominates the increase of the electron temperature and leads to a kink in the mobility-field characteristic. The nonoscillatory positive magnetoresistance is shown to be dependent on the electric field. The negative magnetoresistance of the samples under investigation was studied between 2.4 and 4.2 K. A semiempirical relation of the form $\frac{\ensuremath{\Delta}\ensuremath{\rho}}{{\ensuremath{\rho}}_{0}}=\ensuremath{-}{B}_{1} \mathrm{ln}[1+{B}_{2}(T){B}^{2}]$ was used to analyze the data.

Non-ohmic electron transport on liquid surfaces

A calculation of the electron distribution function and mobility is outlined for electrons on a liquid surface. Electrons are scattered by gas atoms and liquid surface waves. If surface wave scattering dominates, the mobility increases rapidly with increasing electric field in the non-ohmic region.

Low-Temperature Non-Ohmic Electron Transport in GaAs

Low-Temperature Non-Ohmic Electron Transport in GaAs

Application of the electron temperature model to low-temperature non-ohmic transport in GaAs

The electron temperature model and a theory involving a direct solution of the Boltzmann equation are compared with experiment. The experimental data are the field dependence of the conductivity and Hall constant at 4.23°K in GaAs. Only the theory involving a direct calculation of the distribution function appears to explain the experimental observations. This result is surprising since the electron density is about 4 orders of magnitude above that required to justify the electron temperature model.

Low-Temperature Non-Ohmic Electron Transport in GaAs

Low-Temperature Non-Ohmic Electron Transport in GaAs

Application of the electron temperature model to low temperature non-ohmic transport in GaAs

Abstract The electron temperature model and a theory involving a direct solution of the Boltzmann equation are compared with experiment. The experimental data are the field dependence of the conductivity and Hall constant at 4.23°K in GaAs. Only the theory involving a direct calculation of the distribution function appears to explain the experimental observations. This result is surprising since the electron density is about 4 orders of magnitude above that required to justify the electron temperature model.

Low temperature non-ohmic transport in InSb

Abstract A different interpretation from that of Miyazawa and Ikoma is given for their measurements of low temperature non-ohmic Hall effect. The conclusion is drawn that their measurements are not evidence of donor freeze out in InSb. Their results are analyzed in terms of a hot electron theory that shows that the features that they attributed to two band conduction (impurity and conduction band) are due to conduction band electrons.

Effects of non-parabolicity on non-ohmic transport in InAs

Calculations are made by the Monte-Carlo method of non-ohmic effects in InAs at high electric fields. Previous calculations had suggested that a negative resistance effect occurred because of the non-parabolicity of the conduction band. The present calculations, which are believed to be more accurate, indicate there is no such negative resistance.

Effects of Nonparabolicity on Non-Ohmic Transport in InSb and InAs

Hot-electron distribution functions, occupation densities, and drift velocities are calculated for InAs and InSb at room temperature, on the assumption that there are polar-optical-phonon interactions only. Exact energy-momentum dispersion and wave functions are taken into account. The distribution function and occupation density are compared with calculations based on an electron-temperature model in parabolic bands. These calculations give essentially the same result for the average energy prior to collective breakdown, but a rather different shape for the distribution function. The drift velocity, as calculated here, remains a linear function of the field up to fields well above avalanche breakdown. This behavior seems to be confirmed by experiment.