Study on Web Hub System of Nano-Eledronic Device Modeling

在本课题研究的规定时间内，取得了以下成果.基于紧束缚近似的半导体能带结构计算程序的开发实现了任意III-V族化合物半导体的哈密顿量自动生成。我们已经开发了一个新的代码来提取紧束缚（TB）参数的任意晶体，如金刚石，锌，立方或六方晶体结构。该代码利用遗传算法（GA），使我们能够从从头算密度泛函（DFT）能带计算的结果中提取紧束缚参数，而不会陷入局部极小值。因此，我们提取了各种TB参数，从这些参数中我们可以很容易地计算出化合物的能带结构以及光学性质.纳米尺度MOSFET中的量子输运模型我们利用非平衡绿色函数方法分析了纳米尺度器件，特别是十纳米尺寸MOSFET中的量子输运现象。在模拟中，我们使用了我们提取的遗传技术的晶体的材料参数。结果表明，在Si-SiO2界面上发生了表面量子化，电子波从一个电极的尺寸量子化模输运到另一个电极的表面量子化模，再输运到另一个电极的尺寸量子化模.它表明，目前的建模工具是强大的，在纳米尺度的量子效应起着重要作用的器件的分析。

The following results have been successfully achieved during allotted period of this project research.1. Development of Semiconductor Band Structure Calculation Programs Based on Tight-Binding ApproximationAutomatic Hamiltonian generation of arbitrary III-V compound semiconductor has been achieved. We have developed a new code to extract tight-binding (TB) parameters of arbitrary crystals such as a diamond, zinc-blende, cubic, or hexagonal crystallographic structures. This code utilizes a genetic algorithm (GA) which enables us to extract tight-binding parameters from results of ab-initio density functional (DFT) band calculation without falling into local minima. As a result, we have extracted various kinds of TB parameters from which we can readily calculate band structures as well as optical properties of compound semiconductors.2. Quantum Transport Modeling in Nano-scale MOSFETsWe have made use of the non-equilibrium Green's function method to analyze quantum transport phenomena in nano-scale devices, specifically deca-nm size MOSFETs. In the simulation, we have used the material parameters of the crystal we extracted by the GA technique. As a result, it is found that the surface quantization occurs at the Si-SiO2 interface and the electron waves transport from size-quantized modes in one electrode to the surface quatized mode and then to the size-quantized mode in the other electrode. It is demonstrated that the present modeling tool is powerful in the analysis of nano-scale devices where quantum effects play important roles.