Bonding and strain behavior of graphene/boron nitride diaphragm of micro-electro-mechanical system pressure sensor

The van der Waals heterostructure composed of a vertical stack of graphene and hexagonal boron nitride (h-BN) layered materials is an ideal model for manufacturing high-quality graphene devices. This paper proposes a new type of pressure sensor structure, using graphene/h-BN heterostructure on Si/SiO2 substrate as a pressure sensitive film. Through the method of molecular dynamics simulation, the stress-strain relationship between graphene and graphene/h-BN heterostructure was obtained from the molecular atomic level. It is found that the elastic modulus of single-layer graphene is about 907 GPa, and as the temperature increasing higher, the elastic modulus value will become smaller. Furthermore, the mechanical properties and temperature characteristics of the graphene/h-BN heterostructure were analyzed, and the elastic modulus of the heterostructure is 1343 GPa. The mechanical parameters of the heterostructure are less sensitive to temperature than graphene. Secondly, according to density functional theory and CASTEP, the energy change of graphene/h-BN heterostructure bonding and the geometric optimization of three different configurations were analyzed, and the AB type (one carbon is on the nitrogen, the other is on the center of hexagonal boron nitride) is the optimal configuration, and the maximum band gap opening is 3.803 eV. The band structure and density of states of this configuration were calculated. These results provide a certain theoretical basis and basis for the design and manufacture of graphene/h-BN heterostructure pressure sensors.