A molecular dynamics study of the mechanical properties of the graphene/hexagonal boron nitride planar heterojunction for RRAM

Abstract

Due to their high flexibility and precise interface modulation, resistive random access memory (RRAM) devices composed of graphene/hexagonal boron nitride (Gr/h-BN) planar heterojunctions are regarded as a possible solution and have gained a substantial amount of attention. Molecular dynamics simulations with a modified Tersoff potential are conducted to investigate the mechanical properties of three planar heterojunction RRAM molecular models (Gr/h-BN_V1/V2/V3), which are established according to the interface type and atomic position. Among them, the Gr/h-BN_V1 model exhibits the best mechanical properties, including the fracture strength, fracture strain, and Young's modulus, at all simulation temperatures. The extensive simulations reveal the effects of the temperature, aspect ratio, single-vacancy (SV) and Stone-Wales (SW) defects on the tensile strength of Gr/h-BN RRAM models. As the temperature increases from 10 K to 500 K, the fracture strengths of the Gr/h-BN_V1, Gr/h-BN_V2 and Gr/h-BN_V3 models decrease by 12.6%, 59.6% and 12.0%, respectively. It can be observed that when the aspect ratio is 2.83, the comprehensive mechanical properties of the Gr/ h-BN_V1 model are superior to those of the other models. A 6.7% concentration of single atomic defects in the SV_C, SV_B and SV_N models causes decreases in the fracture strength of 28.0 GPa, 33.9 GPa and 22.6 GPa, respectively, indicating that the mechanical properties are more sensitive to the introduction of boron atomic vacancies than carbon and nitrogen atomic vacancies. At all defect concentrations, the decrease in fracture strength and fracture strain caused by SW defects in the SW_CN model is minimized, while the demarcation point of the relative influence of the defect concentration on the tensile strength is 16% in the SW_CB and SW_CC models. Our present work provides useful insights into the application of highly flexible and stretchable Gr/h-BN planar heterojunctions for RRAM devices.