Relaxation of Electron Spin during High-Field Transport in GaAs Bulk

A semiclassical Monte Carlo approach is adopted to study the multivalley spin depolarization of drifting electrons in a doped n-type GaAs bulk semiconductor, in a wide range of lattice temperature ($40<T_L<300$ K) and doping density ($10^{13}<n<10^{16}$cm$^{-3}$). The decay of the initial non-equilibrium spin polarization of the conduction electrons is investigated as a function of the amplitude of the driving static electric field, ranging between 0.1 and 6 kV/cm, by considering the spin dynamics of electrons in both the $\Gamma$ and the upper valleys of the semiconductor. Doping density considerably affects spin relaxation at low temperature and weak intensity of the driving electric field. At high values of the electric field, the strong spin-orbit coupling of electrons in the $L$-valleys significantly reduces the average spin polarization lifetime, but, unexpectedly, for field amplitudes greater than 2.5 kV/cm, the spin lifetime increases with the lattice temperature. Our numerical findings are validated by a good agreement with the available experimental results and with calculations recently obtained by a different theoretical approach.Comment: 14 pages, 6 figure

Self-consistent Monte Carlo particle modelling of small semiconductor elements.

A self-consistent Monte Carlo particle model aimed at a profound physical understanding of small semiconductor components of arbitrary geometries is presented. The simulation technique consists briefly of following the transport histories of individual charge carries in detail. After a discussion of the stochastic distribution of the time of free flight, the scattering mechanisms and the scattering angles of the particles, a brief review of the relevant semiconductor is given. As an example to illustrate the salient points of the technique, the results of simulating a GaAs field-effect transistor will be discussed. The presentation of the transistor characteristics is used to establish a link between theoretical physics and the view of the electrical engineer. A short discussion of statistical phenomena such as noise, negative differential resistivity and substrate currents has also been included

Electromagnetic radiation from hot carriers in FET-devices.

We report on the emission of light from Si MOS and GaAs MES devices. Processes involving band-to-band transitions and a Bremsstrahlung-continuum below the bandgap are shown to exist. Spatially nonuniform emission from the MESFETs is observed. The GaAs results are compared with Monte Carlo simulations