Browsing by Author "Besikci, C."

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Open Access
Dielectric screening effects on electron transport in Ga0.51In0.49P/InxGa1-xAs/GaAs quantum wells
(American Institute of Physics, 2000-04-18) Besikci, C.; Bakir, A. T.; Tanatar, Bilal
The effects of dielectric screening on the two dimensional polar optical phonon scattering and on electron transport in Ga0.51In0.49P/InxGa1-xAs/GaAs (x=0, 0.15, and 0.25) modulation doped heterostructures and high electron mobility transistors are investigated through the ensemble Monte Carlo technique. The two dimensional polar optical phonon scattering rates including and excluding dielectric screening effects are calculated using the self-consistently evaluated electronic states in the quantum well. The calculated scattering rates are compared in order to see the effects of screening on the inter- and intra-subband scattering. Screening significantly lowers the intra-subband polar optical phonon scattering rates in both lattice matched and pseudomorphic structures. This results in a considerable lowering of the critical electric field beyond which negative differential resistance is seen. Screening also modifies the dependence of transport properties on the quantum well parameters. The results of the ensemble Monte Carlo simulations of high electron mobility transistors show that the performance of the device is considerably underestimated, if screening is not included in the calculation of the polar optical phonon scattering rates. (C) 2000 American Institute of Physics.
Open Access
Effects of screening on the two-dimensional electron transport properties in modulation doped heterostructures
(Elsevier, 1998-06) Sen, O.; Besikci, C.; Tanatar, Bilal
The effects of screening on the polar optical phonon scattering rates and on the transport properties of the two-dimensional electron gas in AlGaAs/GaAs modulation doped heterostructures have been investigated through Monte Carlo simulations incorporating the three valleys of the conduction band, size quantization in the Gamma valley and the lowest three subbands in the quantum-well. At typical sheet densities observed in modulation doped field-effect transistors, screening considerably affects the electron transport properties under moderately large fields and at low temperatures, by lowering the intrasubband polar-optical phonon scattering rates especially in the first subband. The results show that screening, which is usually ignored in device Monte Carlo simulations, should be included in the simulation in order to be able to predict the device performance correctly. (C) 1998 Elsevier Science Ltd. All rights reserved.
Open Access
Hydrodynamic approach for modelling transport in quantum well device structures
(Institute of Physics Publishing Ltd., 1998) Besikci, C.; Tanatar, Bilal; Sen, O.
A semiclassical approach for modelling electron transport in quantum well structures is presented. The model is based on the balance equations governing the conservation of particle density, momentum and energy with Monte Carlo (MC) generated transport parameters. Three valleys of the conduction band, size quantization in the Γ valley, and the lowest two subbands in the quantum well are considered by taking the detailed intersubband dynamics into account. The transport parameters of the model are extracted from steady-state MC simulations based on an improved formulation of two-dimensional polar optical phonon scattering including screening effects. The predictions of the proposed model have been found to be in excellent agreement with those of the ensemble MC simulations under both time varying and spatially nonuniform fields. The calculated transport parameters which are of interest for device modelling are presented as a function of the electron energy for the AIGaAs/GaAs quantum well. The model serves as an accurate semiclassical alternative to costly ensemble MC simulations for studying the transport in quantum well structures and for the modelling and optimization of submicron devices based on these structures, such as modulation doped field-effect transistors (MODFETs).