Improved rectification characteristics of the GR/Blue P/GR selector by doping: First-principles study

In this paper, a graphene (GR)/monolayer (ML) blue phosphorous (Blue P)/GR selector was studied based on the first-principles theory. Due to different contact edges, four GR–Blue P lateral heterojunctions were constructed, namely, armchair–armchair (A–A), zigzag–armchair (Z–A), armchair–zigzag (A–Z), and zigzag–zigzag (Z–Z). As demonstrated by the binding energy and Mulliken population, we found that the Z–Z heterojunction was relatively stable. Furthermore, a GR/Blue P/GR selector based on the Z–Z heterojunction interface was proposed with a nonlinear (NL) coefficient is 105. However, the drive current of this device was insufficient. A P atom of the resistive layer was separately substituted with four different atoms (Ni, Cu, N, and Cl) to effectively improve selector performance. The energy band structure was half-metallic when doped with Ni or Cu while the others still maintained semiconductor characteristics, and the bandgap was significantly reduced. The Schottky barrier height and width of the interface (GR–Blue P), with Cl as the substituted impurity, were the smallest, leading to a three order of magnitude increase in the NL coefficient. The calculation shows that GR/Blue P/GR devices can be integrated as selectors in Resistive switching Random Access Memory (RRAM) arrays. This work also has a certain guiding significance for manufacturing new types of two-dimensional lateral selector apparatuses.