Density functional theory study on Ti/h-BN interface in resistance random access memory device

Abstract

By applying density functional theory calculations, we analyzed the intrinsic propensity of the Ti/h-BN interface in a resistive random access memory (RRAM) device upon the existence of a Stone–Wales (SW) defect and boron vacancy (VB). Following the construction of the Ti(001) surface and h-BN(SW) stack, Ti/h-BN interface models with different configurations and terminated sites were proposed, among which h-BN(SW)I/Ti(001)_TN was identified as the most stable interface system according to the binding energy. The charge transfer from Ti(001) toward the h-BN layers, resulting in heavy doping, formed an Ohmic contact in the interface. Moreover, through analysis of structure optimization, an intrinsic tendency of Ti ion migration to pass through the interface was revealed in the presence of SW defects and VB in the h-BN interface layer. The result of the migration barrier suggested that SW defects, especially B–B bond heptagons, provide preferential pathways for the vertical penetration of Ti ions through the interface, whereas VB in defects contribute most to the facilitation of Ti ion migration. Finally, I–V curves of RRAM device models with different interface configurations showed that SW defects and VB in the interface are critical to resistive switching behavior and can improve performance parameters, such as set voltage and current on/off ratios.