Research of quantum transport in silicon integrated devices

本计画的目的是发展一个量子修正的蒙地卡罗（MC）元件模拟器，并研究硅积体元件的量子输运性质。在奈米尺寸MOSFET的实际设计中，必须精确地模拟硅的能带结构，以考虑MOS反型层的能量量子化。在这个项目中，我们第一次成功地将硅导带的椭圆形多通道纳入Monte Calro器件模拟器中，在玻尔兹曼输运方程中对电势进行量子校正。通过与自洽Schrodinger-Poisson方法计算结果的比较，验证了量子修正MC方法的有效性，提出了一种考虑电子-电子相互作用的量子修正MC方法和分子动力学方法的耦合方法.速度-电场特性仿真 关于我们 在高电场区，用我们新发展的方法计算的饱和速度与实验结果符合得很好，表明饱和速度依赖于表面电子浓度。此外，我们开始将量子修正MC方法扩展到全三维模拟，以应用于新型MOS器件如FinFET。我们还研究了纳米Si-MOSFET的准弹道输运。我们发现，所谓的“载流子扩散过程”中起着重要的作用，从源极到沟道的载流子注入行为。因此，在MOSFET的实际工作中，假设载流子注入为半费米-狄拉克函数的理想注入模型是不正确的。当沟道长度小于20 nm时，由于弹道电子的增加，漏电流增强，这种增强一直持续到亚10 nm区域。这些发现将为探索Si-MOSFET的缩放极限提供重要的科学指导。少

This project aims to develop a quantum-corrected Monte Carlo (MC) device simulator, which had been originally proposed by the head investigator of this project, and to study the quantum transport properties of silicon integrated devices.In practical design of nano-scaled MOSFETs, an accurate modeling of silicon band structure is necessary to consider the energy quantization in a MOS inversion layer. In this project, we first succeeded in incorporating the ellipsoidal multivalleys of a silicon conduction band into a Monte Calro device simulator in terms of a quantum correction of potential in the Boltzmann transport equation. The validity of the quantum-corrected MC technique was verified by comparing the simulated results with those calculated by a self-consistent Schrodinger-Poisson method.We proposed a coupled method of quantum-corrected Monte Carlo and molecular dynamics approaches to take electron-electron interactions into account. The velocity-electric field characteristics simul … More ated by using our newly developed method agreed well with the experimental results in high electric field regime, which indicated that the saturation velocity depends on surface electron concentration. Furthermore, we began to extend the quantum-corrected MC method to a full three-dimensional simulation so as to apply it to a new type of MOS devices such as FinFET.We also investigated a quasi-ballistic transport in nano-scaled Si-MOSFETs. We found that the so-called "carrier diffusion process" plays an important role in a carrier injection behavior from source to channel. Consequently, the perfect injection model, where a hemi Fermi-Dirac function is assumed for the carrier injection, is not correct in the practical operation of MOSFETs. We also found that the drain current enhances due to an increase of ballistic electrons when the channel length becomes shorter than 20nm, and the drain current enhancement persists until a sub-10nm regime. These findings will be important scientific guidelines for exploring the scaling limit of Si-MOSFETs. Less