Research of quantum transport in silicon integrated devices

本项目的目的是开发一个量子修正的蒙特卡罗(MC)器件模拟器，研究硅集成器件的量子输运特性。在实际的纳米MOSFET设计中，为了考虑MOS反型层中的能量量子化，需要对硅能带结构进行精确的建模。在这个项目中，我们首次成功地将硅导带的椭球多谷结合到蒙特卡罗器件模拟器中，这是通过对玻尔兹曼输运方程中的势进行量子修正来实现的。通过将模拟结果与自洽薛定谔-泊松方法的计算结果进行比较，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蒙特卡罗和分子动力学耦合方法。模拟…的速度-电场特性用新方法计算得到的饱和速度与实验结果吻合较好，表明饱和速度与表面电子浓度有关。此外，我们开始将量子修正的MC方法扩展到全三维模拟，以便将其应用于新型的MOS器件，如FinFET。我们还研究了纳米级Si-MOSFET中的准弹道输运。我们发现所谓的“载流子扩散过程”在从源到沟道的载流子注入行为中起着重要的作用。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。我们还发现，当沟道长度变短到20 nm时，由于弹道电子的增加，漏电流增加，并且漏电流增加一直持续到10 nm以下。这些发现将为探索硅MOSFET的尺寸极限提供重要的科学指导。较少

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