电-声子散射对石墨烯场效应管暂态输运性质的影响

项目名称： 电-声子散射对石墨烯场效应管暂态输运性质的影响

项目编号： No.11304205

项目类型： 青年科学基金项目

立项/批准年度： 2014

项目学科： 数理科学和化学

项目作者： 王斌

作者单位： 深圳大学

项目金额： 25万元

中文摘要： 响应速度是描述纳米电子器件运算性能的一个重要指标。通过测量暂态过程中电流随时间的演化，人们可以获得纳米电子器件的响应速度。理论上，电子器件的响应速度不仅依赖于电子的固有时间尺度，也跟器件中的相互作用密切相关，其中最重要的是电-声子相互作用。在本项目中，我们拟采用非平衡格林函数方法，发展描述纳米体系暂态输运性质的理论。在该理论中，我们既要考虑电子的固有时间尺度，也要考虑由电-声子非弹性散射引起的弛豫时间尺度。另一方面，考虑到电子器件本身的结构特征在输运过程中扮演着非常重要的角色，我们拟将该描述电子器件暂态输运性质的理论和密度泛函理论相结合，从第一性原理计算出发研究不同石墨烯场效应管的暂态输运性质，进而分析各种临界参数，包括声子、偏压、温度、石墨烯条带的宽度、场效应管的沟道长度、杂质（比如N/B掺杂）、衬底（比如SiC）等对器件响应速度的影响。

中文关键词： 暂态输运；石墨烯；电子-声子耦合；密度泛函理论；非平衡格林函数

英文摘要： The operational speed is one of the most important indicators for evaluating the merits of emerging nanoscale electronic devices. The most direct understanding of the operational speed comes from analyzing the transient dynamic response of the device, i.e. the time-dependent transient current which is induced by the sudden variation of the external bias voltage. The intrinsic time scale of the transient current in a nanoscale system is largely determined by such factors as the dwell time - which measures how long the electron spends in the system; the first passage time - which measures the time needed for direct transmission, etc.. These scales are the simplest to theoretically analyze. However, in any molecular devices under practical operational conditions, the transient current is not only dependent on the intrinsic time scales, but also critically limited by interactions: the most important one is the electron-phonon (e-p) interaction that provides the e-p inelastic relaxation time scale. On the other hand, for the emerging nanoscale devices where the atomic details of the nanostructures play a dominant role for quantum transport, the dynamics of transient current under e-p scattering has never been investigated from atomistic first principles. This unfortunate state of affair must be resolved before quanti

英文关键词： transient transport；graphene；electron-phonon coupling；density functional theory；non-equilibrium Green's function