W. Cai

Simulation of ultrafast relaxation of photoexcited electrons via analytical distribution functions

Abstract We propose an analytic representation to study electron relaxation during an ultrafast process in a semiconductor quantum well. Gauss-type energy functions are used to simulate the peaks of nonthermal electrons, while the background electrons are described by a Boltzmann distribution function. The time variations of parameters describing the amplitudes and widths of Gauss-type functions, and the temperature of background electrons, are determined by solution of the Boltzmann equation with electron-electron and electron-phonon interactions.

Electron transport in semiconductors under a strong high frequency electric field

Abstract We propose an analytical approach to study the electron transport in semiconductors when a strong high frequency (HF) electric field is applied together with a weak direct current (DC) electric field. We derive a set of dynamic equations, from which the amplitude and phase of each harmonic component of the electron drift velocity and the electron temperature can be obtained. Our calculation shows that the DC conductivity in an n -GaAs sample decreases dramatically with increase of the first and second harmonic applied electric fields and definitely becomes negative.

Electron-Hole-Phonon Coupling In Semiconductor Quantum Wells

We study the transport of the photoexcited quasi-2D electron-hole (e-h) plasma in a p-doped semiconductor quantum well, where electrons are a minority. Using the drifted temperature model for both electrons and holes and introducing a coordinate transformation to the center-of-mass system, separately, for electrons and holes, we obtain a set of coupled equations for the drift velocities and the temperatures of electrons and holes. We show that negative absolute mobility for minority electrons occurs at low temperature and under a weak electric field due to the electron-hole drag. In a strong electric field and at room bath temperature, our results show that the electrons are heated much more than the holes. The electron mobility is smaller in the presence of the hole plasma than in the absence of holes. These results are in agreement with experiments.