基于二维纳米材料的半导体器件模拟方法研究

A self-consistent simulator based on Tight-binding-NEGF and 3D Poisson equation solver is developed by our group for graphene nanoribbons based devices. Based on the work we have done, the device simulation method for the two-dimensional nanomaterial based semiconductor devices including transition metal dichalcogenides (such as MoS2 ) and Silicene will be developed. .The method to correctly produce relevant electronic structure information including the band structure, density of states, Fermi energy for the two-dimensional nanomaterial with transition metal/sp3 hybridization will be investigated. The carrier transport mechanism of the two-dimensional nanomaterial will be evaluated and modeled. The reasons that the effective mobility of the two-dimensional nanomaterial based semiconductor devices degradation seriously will be investigated. The scattering model including phonon scattering, surface phonon scattering, surface roughness scattering and the other scattering mechanism which degradation the effective mobility will be modeled. .The method to simulate time-dependent transport in low-dimensional by using the nonequilibrium Green's functions (NEGF) especially including the scattering effect will be investigated. By combining NEGF-DFT with the NEGF-TB, a novel multi-scale modeling and simulation framework based on the nonequilibrium quantum transport will be developed. The software of device Simulation from band structure, transport properities to I-V characteristics for the two-dimensional nanomaterial based semiconductor devices will be developed, verified and calibrated. The works we will finish are the key points for the challenge of device simulating for nano-scale, low-dimensional semiconductor devices. Our work can help to develop CAD tool for the next generation of semiconductor devices.

本项目将在前期单层石墨烯纳米带器件模型、模拟研究及量子输云的含时模拟方法研究基础上，进一步开展基于过渡金属二硫化物等二维纳米材料的器件的模拟方法研究，发展适于过渡金属或sp3杂化等复杂情况下的电子结构计算方法，研究适于二维纳米材料特点的输运模型和模拟方法，研究影响基于二维材料半导体器件中载流子迁移率下降的原因，建立相应的模型，探索研究含时量子输运的模拟方法，发展从能带，输运直到I-V特性的基于二维纳米材料的原子级器件模拟方法，编写相应的程序并开展可计算性研究。其中电子结构计算、计入散射的量子输运模型与方法以及含时量子输运的模拟方法均是纳米尺度低维电子器件模拟中的关键共性问题，这些问题的突破将为我国新一代电子器件的研究提供理论基础和计算机辅助设计工具。

在过渡金属二硫化物二维纳米材料电子结构、应变效应、输运机理、散射机制及相应模型与模拟方法等方面开展了研究，基于密度泛函理论计算了二维和一维过渡金属二硫化物（MoS2，WS2）的电学特性，研究了层数，应力对二维过渡金属二硫化物的电学特性；研究了宽度以及钝化方式对过渡金属二硫化物纳米带的电子结构的影响；提出了有利于提高纳米带稳定性和载流子迁移率的钝化方式。开发了适于过渡金属二硫化物二维纳米材料的蒙特卡罗模拟程序，对单层二硫化钼中的载流子输运进行了模拟和验证，研究了单层二硫化钼中载流子的高场非线性输运，揭示了光学声子和声学声子对单层二硫化钼中载流子的不同作用；建立了考虑高k栅介质对外界杂质电荷的屏蔽效应和高k栅介质中的远程声子散射的散射模型，利用所建立的模型与模拟程序，解释了使用高k栅介质之后的过渡金属二硫化物二维纳米材料载流子迁移率远远低于只考虑声子散射情况下的载流子迁移率的原因，为基于过渡金属二硫化物二维纳米材料的器件设计和优化提供了理论基础和工具。一年来来我们在国内外核心刊物和国际会议上接收或发表论文5篇，其中被SCI收录1篇、另外2篇已接收的论文也将发表在SCI收录的刊物上。