1,721,064 research outputs found
An Alternative Solution of the Boltzmann Equation: The Scattered Packet Method
No full textInternational audienc
Time-dependent Analysis of the Coupled Hot-Carrier-Hot-Phonon Boltzmann Equations
No full textInternational audienc
Microscopic Simulation of Electronic Noise in Semiconductor Unipolar Structures
No full textInternational audienc
Effect of phonon confinement in quantum well systems
No full textWe discuss the role of LO-phonons confinement in quantum well systems, by comparing two different phonon models that have been proposed in the literature. A critical discussion concerning the use of macroscopic approaches for the description of phonons in two dimensional systems is presented. We use a Monte Carlo simulation which includes nonequilibrium phonon effects as well as carrier-carrier scattering to determine the effect of phonon confinent on the relaxation of photoexcited carriers in A1GaAs-GaAs quantum wells. Good agreement with available experimental data is found. Even at low excitation densities, intercarrier scattering and phonon reabsorption are important, and need to be taken into account in the interpretation of experimental data
Femtosecond phenomena in III-V semiconductors
No full textWe present a Monte Carlo study of ultrafast phenomena in polar semiconductors, focusing on the relaxation of photoexcited carriers in bulk GaAs, InP, and in AlGaAs/GaAs quantum wells. The importance of intercarrier interaction and carrier-phonon scattering are discussed. Very good agreement with experimental results obtained with photoluminescence and Raman spectroscopy is found. A novel method for the treatment of the electron-electron scattering via a molecular-dynamics algorithm is also presented and compared with previous approaches
Hot phonons in quantum wells system
No full textWe present an investigation of non-equilibrium LO-phonon effects in quantum well systems. Phonon confinement is taken into account by considering esplicitly slab modes in the formulation of Fuchs and Kliever. With respect to the “standard” case, where a tridimensional dispersion is used for the LO phonons, the electron-phonon interaction is riduced as result of phonon confinement. We use the Monte Carlo (MC) scheme, which allows the simultaneous study of the coupled electron and phonon dynamics, without requiring any sort of assumption on the respective distribution function. It should be pointed out that the quantization of the phonon wavevector in the direction perpendicular to the interface completely solves the normalization problems of the hot-phonon calculation in 2D-systems. For the case of photoexcitation in AlGaAs-GaAs quantum wells we observe a reduction in the cooling rate due to the reabsorption of hot phonon
Monte Carlo studies of nonequilibrium phonon effects in polar semiconductors and quantum wells. I. Laser photoexcitation
No full textThe present paper illustrates a series of theoretical results on nonequilibrium phonon effects based on a novel Monte Carlo algorithm. The details of the numerical procedure are given. No assumptions on the form of the phonon or the electron distributions are required. The main emphasis is given to the study of LO-phonon perturbations as a result of the relaxation of photoexcited carriers in polar semiconductors. Bulk GaAs and InP, as well as GaAs-AlxGa1-xAs heterostructures are analyzed. Good agreement is found with available experimental results from time-resolved luminescence and Raman measurements. The strong phonon emission by the high-energy photoexcited electrons in the first stage of their relaxation (within a few tenths of a picosecond) is found to drive the phonon distribution strongly out of equilibrium. After the excitation, reabsorption of the emitted phonons by the carriers and nonelectronic phonon-decay processes bring the distribution back to its equilibrium value
Monte Carlo studies of nonequilibrium phonon effects in polar semiconductors and quantum wells. II. Non-Ohmic transport in n-type gallium arsenide
No full textEffects of LO-phonon disturbances on the transient and steady-state high–dc-field response of n-type gallium arsenide are studied by implementing the simulation of nonequilibrium phonon distributions into the conventional Monte Carlo algorithms for hot-carrier transport in semiconductors. Strong LO-phonon amplification is found for the whole range of fields, carrier densities, and temperatures of interest. At room temperature the phonon disturbances lead to enhancements of up to 20% of the steady-state velocity at low fields and to reductions of up to 10% for fields around and above the maximum of the velocity-field characteristics. However, detailed phase-space restrictions for LO-phonon reabsorption prevent a noticeable interference of the phonon buildup with the transient velocity overshoot
- …
