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

Synthesis, Structure, and DFT Analysis of the THF Solvate of 2‐Picolyllithium: A 2‐Picolyllithium Solvate with Significant Carbanionic Character

Previous studies of different solvates of 2-methylpyridyllithium (2-picolyllithium) have uncovered electronic structures corresponding to aza-allyl and enamido resonance forms of the metallated pyridine-based compounds. Here, we report the synthesis and characterization of [2-CH2Li(THF)2C5H4N], a new THF solvate. X-ray crystallographic studies reveal a dimeric arrangement featuring a non-planar eight-membered [NCCLi]2 ring, in which the primary cation-anion interaction is between the central Li atom and the C atom of the deprotonated methyl group [length, 2.285(2) Å], suggesting a new carbanionic resonance structure for this 2-picolyllithium series. The significant carbanionic character of [2-CH2Li(THF)2C5H4N] was confirmed by gas-phase DFT calculations [B3LYP/6-311+G(d)] with the calculated electron density interrogated by means of quantum theory of atoms in molecules (QTAIM) and natural bond orbital (NBO) analyses. For comparison these computational analyses were also performed on the literature structures of [2-CH2Li(2-Picoline)C5H4N] and [2-CH2Li(PMDETA)C5H4N]. In a reactivity study, [2-CH2Li(THF)2C5H4N] was found to undergo nucleophilic addition to pyridine to generate dipyridylmethane in a good yield

A regioselectively 1, 1',3 ,3'-tetrazincated ferrocene complex displaying core and peripheral reactivity

Regioselective 1,1′,3,3′-tetrazincation [C-H to C-Zn(tBu)] of ferrocene has been achieved by reaction of a fourfold excess of di-t-butylzinc (tBu2Zn) with sodium 2,2,6,6-tetramethylpiperidide (NaTMP) in hexane solution manifested in the trimetallic iron-sodium-zinc complex [Na4(TMP)4Zn4(tBu)4{(C5H3)2Fe}], 1. X-ray crystallographic studies supported by DFT modelling reveal the structure to be an open inverse crown in which two [Na(TMP)Zn(tBu)Na(TMP)Zn(tBu)]2+ cationic units surround a {(C5H3)2Fe}4- tetraanion. Detailed C6D6 NMR studies have assigned the plethora of 1H and 13C chemical shifts of this complex. It exists in a major form in which capping and bridging TMP groups interchange, as well as a minor form that appears to be an intermediate in this complicated exchange phenomenon. Investigation of 1 has uncovered two distinct reactivities. Two of its peripheral t-butyl carbanions formally deprotonate toluene at the lateral methyl group to generate benzyl ligands that replace these carbanions in [Na4(TMP)4Zn4(tBu)2(CH2Ph)2{(C5H3)2Fe}], 2, which retains its tetrazincated ferrocenyl core. Benzyl-Na π-arene interactions are a notable feature of 2. In contrast, reaction with pyridine affords the crystalline product {[Na·4py][Zn(py∗)2(tBu)·py]}∞, 3, where py is neutral pyridine (C5H5N) and py∗ is the anion (4-C5H4N), a rare example of pyridine deprotonated/metallated at the 4-position. This ferrocene-free complex appears to be a product of core reactivity in that the core-positioned ferrocenyl anions of 1, in company with TMP anions, have formally deprotonated the heterocycle

Remotely screened electron-impurity scattering model for nanoscale MOSFETs

The ionized impurities within the channel of nanoscale MOSFETs are shown to be strongly remotely screened by the close proximity of the highly doped, degenerate source and drain regions due to polarization charge effects. The position of the ionized impurity within the channel region controls the strength of the remote screening due to polarization charges induced in the source and drain, which increase heavily as the channel screening length exceeds the channel length. A remotely screened ionized impurity scattering potential is calculated based on an exact solution to Poisson's equation for a model system. This scattering potential includes the polarization charge effects from the source and the drain which may contribute separately or in combination depending on the position of the ionized impurity and the channel screening length. A scattering model is developed based on a simplified form of this scattering potential that is suitable for use in Monte Carlo simulations. The resulting scattering model is analysed and is shown to increase the ionized impurity mobility in the channel by a noticeable amount

The influence of polarisation and image charges on Electron-Impurity Scattering in High Degeneracy, Nanometre Scale Silicon wrap-round gate MOSFETs - art. no. 012009

Atomistic impurities in the channel of a nano-wire silicon MOSFET with wrapround gate and highly doped and degenerate source and drain are shown to be strongly screened by polarisation (image charge effects) arising from carriers that are confined to source and drain when the channel screening length exceeds the channel length. The image charge effects on a given atomistic ionized impurity depend significantly on its location in the channel. The model is based on an exact analysis of the Poisson equation using Fourier-Bessel analysis in cylindrical coordinates. Close to source or drain the analytically computed total and differential scattering rates correspond to a form of dipole scattering. The source and drain may separately or together contribute to the screening of the atomistic impurity depending on its location and the channel screening length. The net effect of the infinite sequence of fully developed screened image charges induced by the atomistic impurity is to substantially reduce impurity scattering by at least an order of magnitude and to enhance the back scattering. The theory is illustrated for a 5 nm channel devic

Comparison of Si <100> and <110> crystal orientation nanowire transistor reliability using Poisson–Schrödinger and classical simulations

In this paper we perform trap sensitivity simulation analysis of square nanowire transistors (NWTs), comparing Poisson–Schrödinger (PS) and classical solutions. Both approaches result in very different electrostatic behaviour due to strong quantum confinement effects in ultra-scaled NWTs such as the Si NWTs presented in this work. Statistical distributions of traps are investigated, modelling the steady state impact of Random Telegraph Noise and Bias Temperature Instabilities for two crystal orientations. Statistical simulations are performed to evaluate the reliability impact on threshold voltage and ON current, emphasising the importance of both confinement and trap distribution details for the proper assessment of reliability in nanowire transistors

Discrete Dopant Impact on the 7 nm Nanowire Transistor Performance

No abstract available