Monte Carlo study of current variability in UTB SOI DG MOSFETs

Riddet, Craig (2008) Monte Carlo study of current variability in UTB SOI DG MOSFETs. PhD thesis, University of Glasgow.

Abstract

The scaling of conventional silicon based MOSFETs is increasingly difficult into the nanometer regime due to short channel effects, tunneling and subthreshold leakage current. Ultra-thin body silicon-on-insulator based architectures offer a promising alternative, alleviating these problems through their geometry. However, the transport behaviour in these devices is more complex, especially for silicon thicknesses below 10 nm, with enhancement from band splitting and volume inversion competing with scattering from phonons, Coulomb interactions, interface roughness and body thickness fluctuation.

Here, the effect of the last scattering mechanism on the drive current is examined as it is considered a significant limitation to device performance for body thicknesses below 5 nm. A simulation technique that properly captures non-equilibrium transport, includes quantum effects and maintains computational efficiency is essential for the study of this scattering mechanism. Therefore, a 3D Monte Carlo simulator has been developed which includes this scattering effect in an ab initio fashion, and quantum corrections using the Density Gradient formalism. Monte Carlo simulations using `frozen field' approximation have been carried out to examine the dependence of mobility on silicon thickness in large, self averaging devices. This approximation is then used to carry out statistical studies of uniquely different devices to examine the variability of on-current. Finally, Monte Carlo simulations self consistent with Poisson's equation have been carried out to further investigate this mechanism.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Keywords: MOSFET, Monte Carlo, Double Gate, SOI, Density Gradient, Variability, Body Thickness Variations, Surface Roughness Scattering
• Subjects: T Technology > TK Electrical engineering. Electronics Nuclear engineering
• Colleges/Schools: College of Science and Engineering > School of Engineering
• Supervisor's Name: Asenov, Prof Asen and Roy, Dr Scott A.
• Date of Award: 2008
• Depositing User: Mr Craig Riddet
• Unique ID: glathesis:2008-88
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 07 Oct 2008
• Last Modified: 10 Dec 2012 13:15
• URI: https://theses.gla.ac.uk/id/eprint/88