Research On Interfacial Thermal Conductance In Graphene/Black Phosphorus Heterogeneous Structures

As an important part of two-dimensional materials,Black phosphorus?BP?has attracted wide attention in the world.However,in ambient environment,the phosphorous atoms of BP can react with oxygen and water easily.Thus this property limits the application and development of the black phosphorous-electronic devices.To prevent such chemical reaction or isolate BP from oxygen and water,the most convenient and efficient method is wrapping/covering BP by other more environment-inert materials.In particular,graphene is considered as the best coverage due to the excellent thermal,electrical and mechanical properties.It also has some great physical properties which is lacking in the black phosphorus.When BP is covered by few-layer graphene,thermal transport through the BP/Gr interface is the major route for heat dissipation.However,the BP/Gr interfacial layers are coupled by the weak van de Waals?vdWs?interactions and the inherent lattice mismatch leads to low interfacial thermal conductance.Since thermal conductance limits the maximum current density,the poor thermal performance of a heterogeneous structure limits its application in Micro/Nano-Electro-Mechanical Systems.The accumulated Joule heat nucleates thermal hot spots,and potentially causes failure of devices.Therefore,it is of great significance to improve the performance of interfacial thermal conductance?ITC?.This problem is studied through molecular dynamics method in this paper.The research results are as follows:?1?Two critical parameters,P_cr=0.28GW/m²,the maximum heat power density of maintaining thermal stability,and P_max=6.52GW/m²,the maximum heat power density with which the system can be loaded,have been identified.The results can provide a theoretical basis for the design of black phosphorous-electronic devices.?2?The system size effect and temperature effect on the ITC of BP/Gr have been studied.The results of the size effect show that magnitude of ITC increases with the increasing N_Gr?the number of graphene layers?when the number of BP layers N_BP is fixed at 3,while it is not sensitive to the thickness of BP layers.The maximum G=89.08MWm^-2K^-1 is obtained at N_Gr=?according to the exponential fitting relationship.Moreover,the results of the temperature effect demonstrate that ITC increases with the increasing environment temperature.?3?Applying strain engineering and defect engineering are both effective methods to tune the heat transport across BP/Gr interface.The compression strain can increase the ITC more than 16 times.By introducing a vacancy defect of graphene at the interface,the ITC can be increased about 2.3 times.