Showing 5 results for Moravvej-Farshi
K. Saghafi, M. K Moravvej-Farshi, R. Faez, A. Shahhoseini,
Volume 5, Issue 4 (December 2009)
Abstract
In this paper, we have investigated the effects of asymmetry in the source and drain capacitance of metallic island single electron transistors. By comparing the source and drain Fermi levels, in the ground and source referenced biasing configurations, with the island’s discrete charging energy levels for various gate voltages, we have derived a set of closed form equations for the device threshold voltage. Extending our technique, for the first time, we have also modeled the “kink effect” appearing in the device ID-VDS characteristic, next to the threshold voltage. To demonstrate how accurate the calculated values of the threshold and kink voltages obtained from the analytically derived formulas are, next, we have used the master equation based on the orthodox theory to simulate the device parameters, numerically. Comparisons of the numerical results, obtained from both techniques, have demonstrated the tolerances in our analytical calculations, for the worst case, are less than 1%.
R. Yousefi, M. K. Moravvej-Farshi, K. Saghafi,
Volume 6, Issue 2 (June 2010)
Abstract
In this paper, using the neural space mapping (NSM) concept, we present a
SPICE-compatible modeling technique to modify the conventional MOSFET equations, to
be suitable for ballistic carbon nanotube transistors (CNTTs). We used the NSM concept in
order to correct conventional MOSFET equations so that they could be used for carbon
nanotube transistors. To demonstrate the accuracy of our model, we have compared our
results with those obtained by using open-source software known as FETToy. This
comparison shows that the RMS errors in our calculated IDS, under various conditions, are
smaller than the RMS errors in IDS values calculated by the existing analytical models
published by others.
M. Moravvej-Farshi, F. Esmailifard, K. Saghafi,
Volume 7, Issue 1 (March 2011)
Abstract
We present an optimized design for GaAs/AlGaAs quantum cascade lasers operating at 4.1THz. This was based on a three-well active module with diagonal radiative transition. This was performed by modifying the existing model structure, to reduce the parasitic anticrossings (leakage currents) as well as the optical gain linewidth. While the gain FWHM was reduced by more than 50% the gain peak was increased by about 23.3%.
A. Khodabakhsh, M. K. Moravvej-Farshi, M. Ebnali-Heidari,
Volume 7, Issue 2 (June 2011)
Abstract
We report the simulation results for impact of nonlinear Kerr effect on band structures of a two dimensional photonic crystal (2D-PhC) with no defect, a PhC based W1-waveguide (W1W), and also Coupled-Cavity Waveguides (CCWs). All PhC structres are assumed to a square lattice of constant a made of GaAs rods of radius r=0.2a, in an air background. The numerical simulation was performed using the nonlinear finite difference time domain (NFDTD) technique. To study the impact of Kerr effect on the photonic band structures, E-polarized lights of peak input intensities 0.5 GW-cm−2≤I≤25 GW-cm−2 have been used. The numerical results have shown that as the input light intensity increases, the band edges for all PhC waveguide structures considered experience red shifts. These numerical results for CCWs also show that the larger the light input intensity, the smaller is the corresponding maximum light group velocity.
S. Haji Nasiri, M. K. Moravvej-Farshi, R. Faez,
Volume 8, Issue 1 (March 2012)
Abstract
Time domain analysis of multilayer graphene nanoribbon (MLGNR) interconnects, based on transmission line modeling (TLM) using a six-order linear parametric expression, has been presented for the first time. We have studied the effects of interconnect geometry along with its contact resistance on its step response and Nyquist stability. It is shown that by increasing interconnects dimensions their propagation delays are increased and accordingly the system becomes relatively more stable. In addition, we have compared time responses and Nyquist stabilities of MLGNR and SWCNT bundle interconnects, with the same external dimensions. The results show that under the same conditions, the propagation delays for MLGNR interconnects are smaller than those of SWCNT bundle interconnects are. Hence, SWCNT bundle interconnects are relatively more stable than their MLGNR rivals.
