Full Hydrodynamic Simulation of GaAs MESFETs

A finite difference upwind discretization scheme in two dimensions is presented in detail for the transient simulation of the highly coupled non-linear partial differential equations of the full hydrodynamic model, providing thereby a practical engineering tool for improved charge carrier transport simulations at high electric fields and frequencies. The discretization scheme preserves the conservation and transportive properties of the equations. The hydrodynamic model is able to describe inertia effects which play an increasing role in different fields of micro- and optoelectronics, where simplified charge transport models like the drift-diffusion model and the energy balance model are no longer applicable. Results of extensive numerical simulations are shown for a two-dimensional MESFET device. A comparison of the hydrodynamic model to the commonly used energy balance model is given and the accuracy of the results is discussed.Comment: 18 pages, LATE

Self-mixing model of terahertz rectification in a metal oxide semiconductor capacitance

Metal oxide semiconductor (MOS) capacitance within field effect transistors are of great interest in terahertz (THz) imaging, as they permit high-sensitivity, high-resolution detection of chemical species and images using integrated circuit technology. High-frequency detection based on MOS technology has long been justified using a mechanism described by the plasma wave detection theory. The present study introduces a new interpretation of this effect based on the self-mixing process that occurs in the field effect depletion region, rather than that within the channel of the transistor. The proposed model formulates the THz modulation mechanisms of the charge in the potential barrier below the oxide based on the hydrodynamic semiconductor equations solved for the small-signal approximation. This approach explains the occurrence of the self-mixing process, the detection capability of the structure and, in particular, its frequency dependence. The dependence of the rectified voltage on the bias gate voltage, substrate doping, and frequency is derived, offering a new explanation for several previous experimental results. Harmonic balance simulations are presented and compared with the model results, fully validating the model’s implementation. Thus, the proposed model substantially improves the current understanding of THz rectification in semiconductors and provides new tools for the design of detectors

When self-consistency makes a difference

Compound semiconductor power RF and microwave device modeling requires, in many cases, the use of selfconsistent electrothermal equivalent circuits. The slow thermal dynamics and the thermal nonlinearity should be accurately included in the model; otherwise, some response features subtly related to the detailed frequency behavior of the slow thermal dynamics would be inaccurately reproduced or completely distorted. In this contribution we show two examples, concerning current collapse in HBTs and modeling of IMPs in GaN HEMTs. Accurate thermal modeling is proved to be be made compatible with circuit-oriented CAD tools through a proper choice of system-level approximations; in the discussion we exploit a Wiener approach, but of course the strategy should be tailored to the specific problem under consideratio

Numerical Simulation of Transient Response in 3-D Multi-Channel Nanowire MOSFETs Submitted to Heavy Ion Irradiation

International audienc

Adhesion and detachment fluxes of micro-particles from a permeable wall under turbulent flow conditions

We report a numerical investigation of the deposition and re-entrainment of Brownian particles from a permeable plane wall. The tangential flow was turbulent. The suspension dynamics were obtained through direct numerical simulation of the Navier–Stokes equations coupled to the Lagrangian tracking of individual particles. Physical phenomena acting on the particles such as flow transport, adhesion, detachment and re-entrainment were considered. Brownian diffusion was accounted for in the trajectory computations by a stochastic model specifically adapted for use in the vicinity of the wall. Interactions between the particles and the wall such as adhesion forces and detachment were modeled. Validations of analytical solutions for simplified cases and comparisons with theoretical predictions are presented as well. Results are discussed focusing on the interplay between the distinct mechanisms occurring in the fouling of filtration devices. Particulate fluxes towards and away from the permeable wall are analyzed under different adhesion strengths

Analytical Models of Effective DOS, Saturation Velocity and High-Field Mobility for SiGe HBTs Numerical Simulation

Abstract-Effective density of state, saturation velocity and high field mobility analytical models for hydrodynamic simulation of silicon-germanium hetero-junction bipolar transistors have been derived

Hydrodynamic Analysis and Responsivity improvement of a metal/semiconductor/metal plasmonic detector

Characteristics improvement of photon/plasmon detectors have been the subject of several investigations in the area of plasmonic integrated circuits. Among different suggestions, Silicon-based Metal-Semiconductor-Metal (MSM) waveguides are one of the most popular structures for implementation of high-quality photon/plasmon detectors in infrared wavelengths. In this paper, an integrated Silicon Germanium (SiGe) core MSM plasmon detector is proposed to detect lambda=1550 nm with internal photoemission mechanism. Performance characteristics of the new device are simulated with a simplified hydrodynamic model. In a specific bias point (V=3 V and the incident optical power of 0.31 mW), the output current is 404.3 uA (276 uA detection current and 128.3 uA dark current), responsivity is 0.89 A/W and the 3-dB electrical bandwidth is 120 GHz. Simulation results for the proposed Plasmon detector, in comparison with the empirical results of a reported Si-based MSM device, demonstrate considerable responsivity enhancement.Comment: 12 pages; 12 figure