Comparison of Quantum Corrections for Monte Carlo Simulation

As semiconductor devices are scaled down to nanometer scale dimensions, quantum mechanical effects can become important. For many device simulations at normal temperatures, an efficient quantum correction approach within a semi-classical framework is expected to be a practical way applicable to multi-dimensional simulation of ultrasmall integrated devices. In this paper, we present a comparative study on the three quantum correction methods proposed to operate within the Monte Carlo framework, which are based on Wigner transport equation, path integrals, and Schrödinger equation. Quantitative comparisons for the strengths and weaknesses of these methods are discussed by applying them to size quantization and tunneling effects.     

Wigner Function-Based Simulation of Quantum Transport in Scaled DG-MOSFETs Using a Monte Carlo Method

Source-to-drain tunneling in deca-nanometer double-gate MOSFETs is studied using a Monte Carlo solver for the Wigner transport equation. This approach allows the effect of scattering to be included. The subband structure is calculated by means of post-processing results from the device simulator Minimos-NT, and the contribution of the lowest subband is determined by the quantum transport simulation. By separating the potential profile into a smooth classical component and a rapidly varying quantum component the numerical stability of the Monte Carlo method is improved. The results clearly show an increasing tunneling component of the drain current with decreasing gate length. For longer gate lengths the semi-classical result is approached.     

Full Quantum Mechanical Simulation of Ultra-Small Silicon Devices in Three-Dimensions: Physics and Issues

The combination of the need for alternative devices and the improvement in process technology has led to the examination of silicon quantum wires for future MOS technology. However, in order to properly model these devices, a full three-dimensional quantum mechanical treatment is required. In this paper, we present the results of a three-dimensional, fully quantum mechanical, self-consistent simulation of a silicon quantum wire MOSFET (Metal Oxide Field Effect Transistor) with a narrow channel (8 nm). A quasi-standing wave is formed in the narrow channel at certain gate voltages as the electron density is trapped in narrow channel. These effects are the result of two competing effects: (1) the interaction of the propagating electrons with the channel dopants, as well as with the dopants in the source and drain of the device. (2) the reflections from the boundaries that form the narrow channel both on the source side and the drain side.     

A Quantum Mechanical Approach for the Simulation of Si/SiO2 Interface Roughness Scattering in Silicon Nanowire Transistors

In this work, we present a quantum mechanical approach for the simulation of Si/SiO₂ interface roughness scattering in silicon nanowire transistors (SNWTs). The simulation domain is discretized with a three-dimensional (3D) finite element mesh, and the microscopic structure of the Si/SiO₂ interface roughness is directly implemented. The 3D Schrödinger equation with open boundary conditions is solved by the non-equilibrium Green’s function method together with the coupled mode space approach. The 3D electrostatics in the device is rigorously treated by solving a 3D Poisson equation with the finite element method. Although we mainly focus on computational techniques in this paper, the physics of SRS in SNWTs and its impact on the device characteristics are also briefly discussed.