Catálogo de publicaciones - libros

For the needs of high electron mobility transistors (HEMTs) optimization a reliable software simulation tool is required. Due to the high electric field in the device channel a hydrodynamic approach is used to properly model the electron transport. We modify an existing hydrodynamic mobility model in order to achieve a better agreement with Monte Carlo (MC) simulation data and measured DC and AC characteristics of AlGaN/GaN HEMTs.

Physics-based numerical simulation of an AlGaN/GaN HEMT with additional A1N interlayer (IL) is carried out using both the drift-diffusion (DD) and hydrodynamic (HD) transport models. Assuming that free electrons are supplied by donor-like surface traps (STs) at the top of the AlGaN layer, we show that the A1N IL increases the 2D electron gas density and reduces the ST occupation. The HD model correctly describes ST recharging due to heating of the channel electrons and subsequent thermionic emission into the AlGaN layer. This recharging has a strong effect on channel transport, leading to the creation of a depletion domain, which expands towards the drain with increasing drain bias. The DD model does not include this effect and the depletion region remains unchanged as the drain bias increases.

Using embedded SRAM as a path, FinFET may enter manufacturing at 32nm. FinFET provides several advantages over the planar MOSFET structure—smaller size, larger current, smaller leakage, and less variation in threshold voltage. A compact model of multi-gate transistors will facilitate their adoption. BSIM-MG is a surface-potential based compact model of multi-gate MOSFETs fabricated on either SOI or bulk substrates. The effects of body doping are modeled. It can also model a double-gate transistor with independently biased front and back gates and asymmetric front and back gate work-functions and dielectric thicknesses.

The compact double-gate MOSFET model HiSIM-DG considering the volume inversion effects is developed solving the Poisson equation iteratively including bulk charge. The developed model reproduces the bias dependence of not only the surface but also the center potential of the silicon layer. The model proves accurate dependence of silicon layer thickness in comparison to the 2 dimensional device simulation results. It is observed that the volume inversion effect prevents devices from performance degradation for a reduction of device sizes.

In this paper, we will present the basic structure and the parameter extraction procedure for a compact model of a NAND Flash memory string working in Spicelike circuit simulators. To the author knowledge, this is the first Spice-like model of a NAND Flash memory string. This model is modular and simple to be implemented. It will allow accurately reproducing both DC and transient behavior of NAND Flash memories without increasing computational effort, thus becoming an indispensable tool for designers to optimize circuits especially in multi-level applications.

The surface-potential-based compact model for quantum effects in planar and double-gate MOSFETs is developed. The surface-potentials at source and drain sides are calculated with the effective field approximation and the quantum charge epxression. The drain current is calculated with the drift-diffusion model and quantum correction of the lateral field. One set of equations is used for both planar and double-gate structures.

A reduction in the number of parameters involved in the statistical compact model parameter extraction is necessary for the development of scalable compact modelling strategy. The impact of size of parameter set on the quality of statistical compact modelling is investigated in detail by HSPICE simulation at both device and circuit levels. Principal component analysis (PCA) is employed on a two- parameter set to demonstrate the possibility to corporate it into scalable statistical compact modelling strategy.

In this work, we first extract Hydrodynamic (HD) parameters from a computationally intensive full-band Monte Carlo (MC) solution via the MOCA simulator. We are then able to achieve good fits between the calibrated HD and MC velocity profile of a near ballistic double gated FET (DGFET). Moreover, we demonstrate good fits using bulk-Si HD parameters between the I–V characteristics of HD simulation and the measured data of deeply scaled Silicon nanowire field effect transistors (SNWFETs).

The performance of carbon nanotube field-effect transistors is analyzed, using the non-equilibrium Green’s function formalism. The role of the inelastic electron-phonon interaction on the both on-current and gate delay time of these devices is studied. For the calculation of the gate delay time the quasi-static approximation is assumed. The results confirm experimental data of carbon nanotube transistors, where the on-current can be close to the ballistic limit, but the gate delay time can be far below that limit.

Metal/carbon nanotube Schottky contacts are studied using particle Monte Carlo Simulation. The developed model is based on the WKB approximation and on the Landauer formula. Results are in fairly good agreement with experimental data.