InGaAs implant-free quantum-well MOSFETs: performance evaluation using 3D Monte Carlo simulation

In this paper we use numerical simulations to evaluate the performance of III-V Implant-Free Quantum-Well (IFQW) MOSFET devices that offer simultaneously high channel mobility, high drive current and excellent electrostatic integrity. Using 3D Monte Carlo simulations we show that to fully understand the performance of this device architecture, Fermi-Dirac statistics and quantum-corrections must be considered to account for the impact of low density-of-states and quantum confinement in the channel layer respectively

Statistical variability in implant-free quantum-well MOSFETs with InGaAs and Ge: a comparative 3D simulation study

Introduction of high mobility channel materials including III-Vs and Ge into future CMOS generations offer the potential for enhanced transport properties compared to Si. The Implant Free Quantum Well (IFQW) architecture offers an attractive design to introduce these materials, providing excellent electrostatic integrity. Statistical variability introduced by the discreteness of charge and granularity of matter has become a key factor for current and future generations of MOSFETs and in this work numerical simulations are used to critically assess the statistical variability in IFQW transistors and compare results with equivalent conventional Si ‘bulk’ MOSFETs

Performance of Vertically Stacked Horizontal Si Nanowires Transistors: A 3D Monte Carlo / 2D Poisson Schrodinger Simulation Study

In this paper we present a simulation study of 5nm vertically stacked lateral nanowires transistor (NWTs). The study is based on calibration of drift-diffusion results against a Poisson-Schrodinger simulations for density-gradient quantum corrections, and against ensemble Monte Carlo simulations to calibrate carrier transport. As a result of these calibrated results, we have established a link between channel strain and the device performance. Additionally, we have compared the current flow in a single, double and triple vertically stacked lateral NWTs

Convergence properties of density gradient quantum corrections in 3D ensemble Monte Carlo simulations

A methodology to include quantum corrections in 3D Monte Carlo simulations is presented, based on the Density Gradient formalism. Three flavours are introduced, with increasing degrees of self-consistency between the current, field and quantum correction and compared in terms of accuracy and impact on the current voltage characteristic

Accurate and efficient modelling of inelastic hole-acoustic phonon scattering in Monte Carlo simulations

Acoustic phonon scattering is known to play an important role in accurately describing hole-transport in semiconductors such as Si and Ge. However, it has been difficult to treat accurately and efficiently due to its dispersion relationship, thus it is often treated as an elastic process or by using constant phonon energy. Here we present an efficient approach for handling inelastic acoustic phonon scattering taking into account the full dispersion relationship. The proposed method unlike previous methods makes no assumption about the carrier distribution function, thus it is suitable for application within a device environment. The model is able to reproduce accurately the velocity-field characteristics over a wide-range of temperatures

Simulation of "ab initio" quantum confinement scattering in UTB MOSFETs using three-dimensional ensemble Monte Carlo

In this paper, we report a 3-D Monte Carlo (MC) simulation methodology that includes complex quantum confinement effects captured through the introduction of robust and efficient density gradient (DG) quantum corrections (QCs), which has been used to introduce “ab initio ” scattering from quantum confinement fluctuations in ultrathin body silicon-on-insulator metal-oxide-semiconductor field-effect transistors (MOSFETs) through the real space trajectories of the particles driven by the DG effective quantum potential and to study the enhanced current variability due to the corresponding transport variations. A “frozen field” approximation, where neither the field nor the QCs are updated, has been used to examine the dependence of mobility on silicon thickness in large self-averaging devices. This approximation, along with the MC simulations that are self-consistent with Poisson's equation, is applied to study the variability of on-current due to random body thickness fluctuations in thin-body MOSFETs at low and high drai

Simulation of hole-mobility in doped relaxed and strained Ge layers

As silicon based metal-oxide-semiconductor field-effect transistors (MOSFETs) are reaching the limits of their performance with scaling, alternative channel materials are being considered to maintain performance in future complementary metal-oxide semiconductor technology generations. Thus there is renewed interest in employing Ge as a channel material in p-MOSFETs, due to the significant improvement in hole mobility as compared to Si. Here we employ full-band Monte Carlo to study hole transport properties in Ge. We present mobility and velocity-field characteristics for different transport directions in p-doped relaxed and strained Ge layers. The simulations are based on a method for over-coming the potentially large dynamic range of scattering rates, which results from the long-range nature of the unscreened Coulombic interaction. Our model for ionized impurity scattering includes the affects of dynamic Lindhard screening, coupled with phase-shift, and multi-ion corrections along with plasmon scattering. We show that all these effects play a role in determining the hole carrier transport in doped Ge layers and cannot be neglecte

Simulation of hole-mobility in doped relaxed and strained Ge

As silicon CMOS begins to reach the limits of its performance, alternative channel materials are being considered. Thus there is renewed interest in employing Germanium for p-MOSFETs, due to the significant improvement in hole mobility as compared to silicon for undoped materials. Of considerable interest from a device point of view is the transport in doped layers. We investigate hole transport at high carrier-densities in doped Germanium layers using a bulk 6-band k·p Monte Carlo simulator, and show that both dynamic and multi-ion screening play a significant role in describing the resulting transport

Monte Carlo simulation study of the impact of strain and substrate orientation on hole mobility in Germanium

The use of alternative channel materials to maintain device performance with scaling for CMOS technology is an active area of research, with Germanium offering an extremely attractive possibility for pMOSFETs in CMOS. In this paper we use full band Monte Carlo transport simulations to investigate the impact of substrate orientation and biaxial strain on hole mobility in bulk Germanium helping to establish a preferential substrate channel orientation that can maximize carrier mobility for these devices