Study On Thermal-mechanical Characteristics Of Graphene/GaN Composite Heterointerface Structure

With the development of science and technology,electronic devices continue to develop towards the direction of integration,and now the characteristic size of electronic devices has reached the nanometer level.Electronic devices generate a lot of heat when working,which needs to be dissipated in time,otherwise,the performance and service life of electronic devices will be greatly affected.Adding graphene into semiconductor materials such as gallium nitride and silicon carbide can greatly improve the heat dissipation performance of materials and improve the reliability of electronic devices.Based on molecular dynamics methods,the thermal and mechanical properties of graphene/gallium nitride interfacial structures under various influencing factors were studied and analyzed in this paper.The main achievements include:(1)The model of graphene/gallium nitride heterogeneous interface structure was established by Materials Studio software.The thermal conductivity of the heterogeneous interface structure under different temperatures,size effect and defect rate was studied by the non-equilibrium molecular dynamics method,and the influencing factors of the thermal conductivity of the heterogeneous interface structure were analyzed.The increase in temperature will lead to a decrease of interfacial thermal conductance.When the temperature increases from 300 K to 1100 K,the interfacial thermal conductance decreases by 61%.The interfacial thermal conductance of heterogeneous interfacial structures decreased with the increase of gallium nitride layers,but first increased and then decreased with the increase of graphene layers.With the increase of gallium nitride defect rate,the interfacial thermal conductance of the heterogeneous interfacial structure increases first and then decreases;with the addition of graphene defect rate,the interfacial thermal conductance increases continuously and finally flattens out.The introduction of appropriate vacancy defects can effectively improve the interfacial thermal conductance of the heterogeneous interfacial structure.(2)The heterogeneous interface structure model of graphene/gallium nitride was constructed.The tensile simulation of the heterogeneous interface structure was carried out in the direction of armchair and sawtooth respectively,and the mechanical properties of the heterogeneous interface structure of graphene/gallium nitride were analyzed and studied.With the increase of temperature,the mechanical properties of the graphene/GaN heterogeneous interface structure decreased continuously.When the temperature increased from 300 K to 1100 K,the Young’s modulus of the heterogeneous interface structure in the armchair direction and the saw bone direction decreased by 5.8%and 15.91%,respectively.Under the same influence factor,The mechanical properties in the direction of the armchair are stronger than those in the direction of the sawtooth.Increasing the number of graphene layers can improve the mechanical properties of the graphene/gallium nitride interfacial structures.When the number of graphene layers increases from one to five,the Young’s modulus of the interfacial structures increases by 50.8%and 48.1%in the armchair direction and sawtooth direction,respectively.When the strain rate is changed during the tensile process,the mechanical properties of the heterogeneous interfacial structures are almost not affected.(3)The graphene/gallium nitride heterogeneous interface structure models with three different interface contacts were constructed to study the effects of interface contacts on the mechanical properties of the heterogeneous interface structures.The results showed that:The mechanical properties of the heterointerface structures were the best when the two sides of graphene were in contact with the end faces of gallium atoms of gallium nitride,and the worst when the two sides of graphene were in contact with the end faces of gallium atoms and the other side was in contact with the end faces of nitrogen atoms.According to the research results of this paper,the thermal and mechanical properties of graphene/gallium nitride heterogeneous interface structures can be regulated,which provides a theoretical basis for the design and development of graphene/gallium nitride composite heterogeneous material electronic devices.