Quantum manifestations in electronic properties of bilayer phosphorene nanoribbons.

Recently, a new edge structure named ZZ (U) has been evidenced as the lowest-energy structure for bilayer phosphorene nanoribbons (PNRs). Owing to strong quantum confinement effects and edge states, width and edge are the two most important factors that influence the properties of PNRs in nanosized microelectronics. In this study, we systematically investigated the evolution of the electronic properties of bilayer PNRs with different edge configurations as the widths vary. The four types of edges explored include ZZ (Pristine), ZZ (Klein), ZZ (Tube), and newly found ZZ (U). As the widths change from 14 to 40 Å, the ZZ (Pristine) are always metallic with edge states penetrating the Fermi level, while the others are semiconductors. The edge states in ZZ (Klein) are located in the two lowest conduction bands. However, in ZZ (U), the edge states are nearly hidden in the bulk band structure, and its carrier transportation exhibits almost perfect 2D layers, nearly eliminating the U-edge influence. Our results pave the way for phosphorene's utilization in electronics and optoelectronics.