Monte Carlo determination of electron transport properties in Gallium Arsenide
A Monte Carlo technique has been used to calculate the electron distribution functions in the (000) and (100) valleys of gallium arsenide. This method avoids having to make any of the conventional approximations used to solve the Boltzmann transport equation, but instead evaluates the distribution function exactly once the scattering rates have been specified. Polar, acoustic and relevant intervalley scattering processes have been included, together with the non-parabolicity and wavevector dependence of the cell-periodic part of the Bloch functions in the (000) valley. The structure found in the distribution function in the (000) valley is interpreted in terms of the energy dependence of the scattering processes, particular reference being made to the prediction of a population inversion for fields in excess of about 10 . The mobility, mean energy, and electron population in each valley and the mean velocity are calculated as functions of the electric field strength, and comparison is made with previous theoretical results and the experimental data.
Available from: Muhammad Hamza El-Saba
- "The solution of semiclassical BTE is carried out by a variety of methods             , among which the iterative methods , the matrix methods , the Monte Carlo method     , the cellular automata method , truncated expansion (usually in Legendre polynomials and spherical harmonics) methods    . In addition, the so-called energy transport model (ETM) and moment methods , which are sometimes called the hydrodynamic model (HDM), have been also used to solve the BTE in the hot carrier regime. "
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ABSTRACT: In this paper we present a complete hydrodynamic model (HDM) describing the transport of charge carriers in semiconductor devices with arbitrary band structure. The model is appended with advanced physical models for almost all the physical parameters of interest in modern Si Devices. These parameters are inter-related via the carrier energy relaxation time. An improved analytical model of the carrier heat flux, on the basis of a fourth moment of the Boltzmann transport equation (BTE), is also presented. In order to resolve the heat evacuation problems in SOI and power devices, the model is coupled with a lattice heat conservation equation. The transport of hot carriers is simulated, according to the proposed HDM and the results are compared with the conventional data obtained using the drift-diffusion model (DDM) and MC simulation. We show from the HD simulation, the effect of the energy relaxation time value on the hot carrier transport in general and the breakdown voltage in particular, of both MOSFETs and bipolar devices.
12/2012; 1(5):118-147. DOI:10.5923/j.msse.20120105.03
Available from: iaesjournal.com
- "Other authors have also pointed out the potential importance of SiC and a few simple devices have been simulated. The MOSFET transistors have been found to be more effective than ordinary transistors made from the semiconductor materials   . In MOSFETs the forming layer of the transistor channel is very thin and the sub-base current is also zero because of their insulation. "
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ABSTRACT: Ensemble Monte Carlo simulations have been carried out to investigate the effects of Gate length and different source-drain bias on the characteristics of wurtzite SiC MOSFETs. Electronic states within the conduction band valleys are represented by non-parabolic ellipsoidal valleys centred on important symmetry points of the Brillouin zone. The following scattering mechanisims, i.e, impurity, polar optical phonon, acoustic phonon, alloy and piezoelectric are inculded in the calculation. Ionized imurity scattering has been treated beyound the Born approximation using the phase-shift analysis. Two transistors with gate lengths of 200 and 400 nm are simulated. Simulations show that with a fixed channel length, when the gate length is decreased, the output drain current is increased, and therefore the transistor transconductance increases. Moreover, with increasing temperature the drain current is reduced, which results in the reduced drain barrier lowering. The simulated device geometries and doping are matched to the nominal parameters described for the experimental structures as closely as possible, and the predicted drain current and other electrical characteristics for the simulated device show much closer agreement with the available experimental data.
09/2011; 1(1). DOI:10.11591/ijece.v1i1.18
Available from: Jérôme Primot
- "Polar optical phonon scattering processes  (emission and absorption) are included for both electrons and holes. They cause a carrier energy loss or gain corresponding to the phonon energy and an anisotropic change in wave vectors. "
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ABSTRACT: A Monte Carlo model is developed for understanding the multiplication process in HgCdTe infrared avalanche photodiodes (APD). A good agreement is achieved between simulations and experimental measurements of gain and excess noise factor on midwave infrared electron injected Hg0.7 Cd0.3Te APD manufactured at CEA/LETI. In both cases, an exponential gain and a low excess noise factor - close to unity out to gains greater than 1000 - were observed on 5.1-mum cut-off devices at 77K. These properties are indicative of a single ionizing carrier multiplication process that is to say in our case the electron. Simulations also predict that holes do not achieve enough energy to impact ionize and to contribute to the gain, which confirms the previous observation. A comparison study is presented to explain the effect of different combinations of scattering processes on the avalanche phenomenon in HgCdTe. We find that alloy scattering with random scattering angle increases multiplication gain and reduces excess noise factor compared to the case including impact ionization only. It also appears that, in the more complete scattering environment, optical phonon scattering delays significantly the onset of avalanche.
Proceedings of SPIE - The International Society for Optical Engineering 04/2008; 7003. DOI:10.1117/12.780501 · 0.20 Impact Factor
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