石墨烯-hBN异质结摩尔图案的声子输运振荡和Fano共振

The room-temperature mobility of graphene device sealed with two pieces of hBN reached the highest value in history, which is only limited by the phonon scattering. In order to enhance the mobility to lead the development of future device applications, the phonon scatting mechanics in the device should be revealed at first. The graphene-hBN hetero-structure forms Moiré pattern among the device. Its phonon scattering induced by Moiré pattern will play a crucial role in electronic device performance. Meanwhile, the Moiré pattern owns the peculiar phonon band structure in the graphene-hBN hetero-structure, thus we can implement phonon transport oscillation and Fano resonance. Therefore, it is a significantly scientific problem to study urgently phonon transport oscillation and Fano resonance in graphene-hBN with Moiré pattern. Based on these presented above, we proposal to carry out studies as follows..(1) By use of the lattice dynamics and the continuum model, we calculate its phonons, and then to study phonon spectrum, phonon filter and phonon gap manipulated by wave length of Moiré pattern. At the same time, we detect its Raman spectrum for verifying its phonon..(2) By use of phonon-phonon scattering law, we study the manipulation of phonon transport by wave length of Moiré pattern, phonon transport oscillation and Fano resonance..(3) From phonon-electron scattering law, we can study the effect of phonon on thermoelectric properties enhancement and the mechanics of electron tunneling. And we can study thermopower and the differential electronic conductance by fabricating the nano-device and the field electric transistor with double-side gates..These three studies above can indicate the mechanics of the phonon transport manipulated by Moiré pattern, phonon transport oscillation and Fano resonance. At the same time, these studies can provide the experimental basis and reference to its thermoelectric enhancement and the performance of field electric transistor.

六角氮化硼封装石墨烯器件的电子迁移率达到历史新高，且只受限于声子散射，为进一步提高电子迁移率引领未来电子器件发展，则必须研究清楚其中声子散射机制。其中石墨烯-hBN二维范德瓦尔斯异质结形成摩尔图案，其声子将对电子散射起主要作用。同时，此摩尔图案具有特殊声子谱，可望实现声子输运振荡和Fano共振等物理新效应。因此，具有摩尔图案的石墨烯-hBN异质结声子输运振荡和Fano共振是一个亟待解决的重要科学问题。因此，本项目拟采用晶格动力学和连续化模型计算其声子，研究带隙的摩尔图案周期调控和声子过滤；用拉曼光谱检验其声子；利用声子-声子散射，研究声子输运振荡和Fano共振；由声子-电子散射，探讨热电性能增强和电子遂穿机制；制作微纳器件和双栅场效应管分别研究热电势和微分电导。以上研究将揭示此异质结中声子带隙调控机制、声子过滤及其输运振荡和Fano共振的原理；同时为其热电性能和场效应管性能的改善提供指导。

本项目主要是针对具有摩尔图案的二维系统中的声子、声子散射机制和热传导进行研究，将进一步提高电子迁移率从而引领未来电子器件发展。由于M. Koshino 和Y. W. Son于2019年Phys. Rev. B上发表了本项目的核心研究内容。因此，本项目转而开展了其他二维材料的研究，并取得如下研究成果：.（1） 利用晶格动力学方法计算了TATB、HMX、PCTFE和PVDF等分子晶体的声子色散关系和其复合物PBX炸药的热导率，得到了氢键对热导率的提高起至关重要的作用；此研究为提高PBX炸药导弹的热导率提供指导。研究了SnS2 薄片在氢等离子体作用下出现减薄和缺陷；而氧等离子体短时间提高SnS2 薄片光电性能，长时间减弱其光电性能。利用桥式法测量了薄层二硫化钼的热导率随电子束辐照产生粗糙度变化规律，即热导率随无序散射变化规律，研究清楚了少层二硫化钼从晶态变成无定形时其热导率发生突变的物理本质。通过碳-银共掺杂实现局域纳米结构从而增强n型碲化铅的热电性能，其ZT值从0.2提高了1.6，此研究结果为热电应用提供了可靠的数据和实现途径。采用第一性原理计算得到了单层T’-MoS2的声子色散，利用群论得到了其本征光学模的不可约表示，并讨论了其拉曼和红外活性。.（2）第一性原理研究双面神MoSSe空位缺陷和掺杂对能带的影响、磷烯作为钠离子电池阳极材料的能带结构、锯齿状H- MoS2纳米带中裂纹对其电学和磁学性质调控、MoS2基二维超晶格半金属铁磁性和手性外尔半金属的轴向反常。.（3）化学气相沉积法在粗糙基底上悬空生长大单晶MoS2、界面控制成核并生长大的单晶NbS2、预沉积MoO3生长晶圆尺寸均匀的单晶MoS2。.（4）利用粘弹性应力累积-剥离机制测量石墨剥离的黏附能、梯度弹性基底优化提高柔性电子器件的循环稳定性和耐用性。.此项目发表了第一致谢此基金项目的SCI论文13篇，其他致谢顺序的论文4篇。