摘要
为解决氮化镓芯片散热问题,采用非平衡分子动力学法,研究工作温度、界面尺寸、缺陷率及缺陷类型对氮化镓/石墨烯/金刚石异质界面热导的影响,通过计算声子态密度和声子参与率,分析界面热传导机理.研究发现,在 100-500 K范围内,温度升高使界面热导增大 2.1倍,重叠因子随温度增加而增加,界面间声子耦合程度增强,界面热导相应增大.当氮化镓层数从 10层增加到 26层时,界面热导降低 75%,分析认为是界面声子耦合程度下降导致.另外,添加 5层石墨烯会导致界面热导降低 74%,分析认为是声子局域化程度加重造成;当缺陷率从 0增大到 10%时,金刚石碳原子缺陷使界面热导提高 40%,缺陷散射增加低频声子数量,改善界面热传导;但镓、氮和石墨烯碳原子缺陷会加重声子局域化程度,均导致界面热导降低.研究结果有助于提升氮化镓芯片散热性能,同时对高可靠性氮化镓器件设计具有指导意义.
Abstract
Gallium nitride chips are widely used in high-frequency and high-power devices.However,thermal management is a serious challenge for gallium nitride devices.To improve thermal dissipation of gallium nitride devices,the nonequilibrium molecular dynamics method is employed to investigate the effects of operating temperature,interface size,defect density and defect types on the interfacial thermal conductance of gallium nitride/graphene/diamond heterostructure.Furthermore,the phonon state densities and phonon participation ratios under various conditions are calculated to analyze the interface thermal conduction mechanism.The results indicate that interfacial thermal conductance increases with temperatures rising,highlighting the inherent self-regulating heat dissipation capabilities of heterogeneous.The interfacial thermal conductance of monolayer graphene structures is increased by 2.1 times as the temperature increases from 100 to 500 K.This is attributed to the overlap factor increasing with temperature rising,which enhances the phonon coupling between interfaces,leading the interfacial thermal conductance to increase.Additionally,in the study it is found that increasing the number of layers of both gallium nitride and graphene leads the interfacial thermal conductance to decrease.When the number of gallium nitride layers increases from 10 to 26,the interfacial thermal conductance decreases by 75%.The overlap factor diminishing with the layer number increasing is ascribed to the decreased match of phonon vibrations between interfaces,resulting in lower thermal transfer efficiency.Similarly,when the number of graphene layers increases from 1 to 5,the interfacial thermal conductance decreases by 74%.The increase in graphene layers leads the low-frequency phonons to decrease,consequently lowering the interfacial thermal conductance.Moreover,multilayer graphene enhances phonon localization,exacerbates the reduction in interfacial thermal conductance.It is found that introducing four types of vacancy defects can affect the interfacial thermal conductance.Diamond carbon atom defects lead its interfacial thermal conductance to increase,whereas defects in gallium,nitrogen,and graphene carbon atoms cause their interfacial thermal conductance to decrease.As the defect concentration increases from 0 to 10%,diamond carbon atom defects increase the interfacial thermal conductance by 40%due to defect scattering,which increases the number of low-frequency phonon modes and expands the channels for interfacial heat transfer,thus improving the interfacial thermal conductance.Defects in graphene intensify the degree of graphene phonon localization,consequently leading the interfacial thermal conductance to decrease.Gallium and nitrogen defects both intensify the phonon localization of gallium nitride,impeding phonon transport channels.Moreover,gallium defects induce more severe phonon localization than nitrogen defects,consequently leading to lower interfacial thermal conductance.This research provides the references for manufacturing highly reliable gallium nitride devices and the widespread use of gallium nitride heterostructures.
基金项目
广西制造系统与先进制造技术重点实验室主任基金(19-050-44-002Z)
2024年度广西高校中青年教师科研基础能力提升项目(2024KY0203)
桂林电子科技大学研究生教育创新计划(2024YCXS016)
2023年广西自治区级新工科研究与实践项目(XGK202309)
国家科技期刊平台
NSTL
万方数据