氮化硼二维材料热输运特性的多物理场调控

Two-dimensional boron nitride (BN) is an insulating material with its thermal conductivity higher than any other two-dimensional materials except graphene. This property enables it to play an important role in chip-level cooling. In its application process, the external measures are needed to manipulate its thermal conductivity and to realize its better combinations with chips. However, both the heat transport mechanism and the mechanism of its physical tuning are not thoroughly investigated. In this project, we will employ the theoretical and experimental methods to investigate the influences of external-strains, electric-field and doping on the heat-transfer property of BN. Theoretically, we are going to simulate the changes of heat-transfer property of BN when applying those physical control measures, and then to analyze the mechanisms inside. Experimentally, we will develop a set of testing system which could constantly detect thermal-conductivity when applying both stains and electric field. We will then apply this system to BN. Our project will provide scientific understructures and theoretical basis for the relevant investigations.

氮化硼二维材料是一种高导热的绝缘材料，其导热系数在二维材料中仅次于石墨烯，该特性决定了这种材料将在微电子芯片级散热发挥重要作用。在其具体使用的过程中，需要使用人为手段调控其热导率并实现与芯片更好地结合。但是目前对于氮化硼热输运机理及应变、电场、掺杂等物理场对其热输运性质影响的机理尚不清楚。本项目将采用理论实验相结合的方法，探索氮化硼系统热传导特性在多物理场调控手段下的变化方式。理论上，将使用第一性原理和分子动力学等方法模拟各调控手段对氮化硼系统热传导特性的影响规律及其协同效应，揭示上述外加因素对氮化硼系统产生影响的机理。实验上，将发展一套适用于施加有应变和电场情况下的热传导测试系统，并将其应用于氮化硼体系。本项目的研究成果将为相关研究提供重要科学依据和理论基础。

本项目研究了氮化硼二维材料热输运特性的多物理场调控特性。理论方面，得到了氮化硼纳米薄膜热导率随层数的变化关系，考察了在施加有应变的条件下电子能带结构、声子振动谱的变化情况。研究了应变和层间相对滑移对氮化硼/石墨烯复合系统电子能带结构、声子振动谱、热导性质的影响情况。探寻多种外加因素情况下提高氮化硼/石墨烯复合系统热导率的有效途径。分析了氮化硼/高分子材料复合系统的热导机理。实验方面，成功搭建氮化硼样品制备平台并得到高质量的氮化硼样品。研究发现电场、应变等外加参量的加入对于提升氮化硼复合系统的热导会发挥显著影响，通过分子枝接等手段可以显著降低该类材料与液体的界面热阻，这对于高效换热器件的设计有积极意义。