Electrostatic Potential Analysis in Polyelectrolyte Brush-Grafted Microchannels Filled with Polyelectrolyte Dispersion

In this study, the model framework that includes almost all relevant parameters of interest has been developed to quantify the electrostatic potential and charge density occurring in microchannels grafted with polyelectrolyte brushes and simultaneously filled with polyelectrolyte dispersion. The brush layer is described by the Alexander-de Gennes model incorporated with the monomer distribution function accompanying the quadratic decay. Each ion concentration due to mobile charges in the bulk and fixed charges in the brush layer can be determined by multi-species ion balance. We solved 2-dimensional Poisson–Nernst–Planck equations adopted for simulating electric field with ion transport in the soft channel, by considering anionic polyelectrolyte of polyacrylic acid (PAA). Remarkable results were obtained regarding the brush height, ionization, electrostatic potential, and charge density profiles with conditions of brush, dispersion, and solution pH. The Donnan potential in the brush channel shows several times higher than the surface potential in the bare channel, whereas it becomes lower with increasing PAA concentration. Our framework is fruitful to provide comparative information regarding electrostatic interaction properties, serving as an important bridge between modeling and experiments, and is possible to couple with governing equations for flow field.

Analog/RF Performance of Triple Material Gate Stack-Graded Channel Double Gate-Junctionless Strained-Silicon MOSFET with Fixed Charges

In this paper, analog/radio frequency (RF) electrical characteristics of triple material gate stackgraded channel double gate-Junctionless (TMGS-GCDGJL) strained-Si (s-Si) MOSFET with fixed charge density is analyzed with the help of Sentaurus TCAD. By varying the various device parameters, the analog/RF performance of the proposed TMGS-GCDG-JL s-Si MOSFET is evaluated in terms of transconductance-generationfactor (TGF), early voltage, voltage gain, unity-powergain frequency ( f max ), unity-current-gain frequency ( f t ), and gain-transconductance frequency product (GTFP). The results confirm that the proposed TMGS-GCDGJL s-Si MOSFET has superior analog/RF performance compared to gate stack-graded channel double gatejunctionless (GS-GCDG-JL) s-Si device. However, the proposed MOSFET has less transconductance and less output conductance when compared with the GS-GCDGJL s-Si device in above threshold region, and reverse trend follows in sub-threshold region.

Physics-Based TCAD Simulation and Calibration of 600 V GaN/AlGaN/GaN Device Characteristics and Analysis of Interface Traps

This study proposes an analysis of the physics-based TCAD (Technology Computer-Aided Design) simulation procedure for GaN/AlGaN/GaN HEMT (High Electron Mobility Transistor) device structures grown on Si (111) substrate which is calibrated against measurement data. The presence of traps and activation energies in the device structure will impact the performance of a device, the source of traps and position of traps in the device remains as a complex exercise until today. The key parameters for the precise tuning of threshold voltage (Vth) in GaN transistors are the control of the positive fixed charges −5 × 1012 cm−2, donor-like traps −3 × 1013 cm−2 at the nitride/GaN interfaces, the energy of the donor-like traps 1.42 eV below the conduction band and the acceptor traps activation energy in the AlGaN layer and buffer regions with 0.59 eV below the conduction band. Hence in this paper, the sensitivity of the trap mechanisms in GaN/AlGaN/GaN HEMT transistors, understanding the absolute vertical electric field distribution, electron density and the physical characteristics of the device has been investigated and the results are in good agreement with GaN experimental data.

Analog/RF Performance of Triple Material Gate Stack-Graded Channel Double Gate-Junctionless Strained-silicon MOSFET with Fixed Charges

In this paper, analog/radio frequency (RF) electrical characteristics of triple material gate stack-graded channel double gate-Junctionless (TMGS-GCDG-JL) strained-silicon (s-Si) MOSFET with fixed charges is analyzed with the help of Sentaurus TCAD. By varying the various device parameters, the analog/RF performance of the proposed TMGS-GCDG-JL s-Si MOSFET is evaluated in terms of early voltage, transconductance generation factor (TGF), voltage gain, unity current gain frequency ( ft ), unity power gain frequency (fmax ), and gain transconductance frequency product (GTFP). The results confirm that the proposed TMGS-GCDG-JL s-Si MOSFET has superior analog/RF performance compared to the gate stack-graded channel double gate-junctionless (GS-GCDG-JL) s-Si MOSFET. However, the proposed device has less transconductance and less output conductance in comparison with the GS-GCDG-JL s-Si MOSFET in strong inversion region, and reverse trend follows in sub-threshold region.

Variability Analysis of Graded Channel Dual Material-double Gate Strained-silicon MOSFET With fixed Charges

In this paper, variability analysis of graded channel dual material (GCDM) double gate (DG) strained-silicon (s-Si) MOSFET with fixed charges is analyzed with the help of Sentaurus TCAD. By varying the different device parameters, the variability analysis of the proposed GCDM-DG s-Si MOSFET is performed with respect to variations in threshold voltage and drain current as the line edge roughness and fluctuations in random dopant, contact resistance, and oxide thickness are considered. The results confirm that the effect of process variations is severe when the device has fixed charges at oxide interface. Moreover, the proposed GCDM-DG s-Si p-MOSFET has less vulnerable to the effects of line edge roughness, fluctuations in oxide thickness and random dopants in comparison with the proposed GCDM-DG s-Si n-MOSFET.

A Numerical Method for Electrical Potential on Membranes with Fixed Charge

The potential developed on a membrane with fixed charge plays crucial roles in many biological and engineering systems. The classic Teorell-Meyer-Siever (TMS) theory gives an analytical expression of the membrane potential only for limited cases of simple solutions. A numerical method that can be applied to the general cases was developed in this study. With a boundary updating scheme, a numerical solution to the Nernst-Planck-Poisson equations was obtained rigorously without the commonly used simplifications and assumptions in previous studies. The features of the membrane potentials with different fixed charges were investigated with this numerical method under various conditions. The validity of this numerical method was verified by identical values of Donnan potential obtained with well-established analytical methods. The suitability and applicability of analytical TMS model were assessed by comparison to the numerical method.