Effect of vacancy defects on transport in all-phosphorene nanoribbon devices from first principles.

Defects in experimentally manufactured phosphorene nanoribbons (PNRs) occur unavoidably, affecting the functionality of PNR-based devices. In this work, we theoretically propose and investigate an all-PNR devices with single-vacancy (SV) defects and double-vacancy (DV) defects along the zigzag direction, accounting for both hydrogen passivation and non-passivation scenarios. We discovered that, in the case of hydrogen passivation, the DV defect can introduce in-gap states, whereas the SV defect can result in p-type doping. The unpassivated hydrogen nanoribbon exhibits an edge state with a considerable influence on the transport properties, which also masks the effect of defects on transport; furthermore, it demonstrates the phenomenon of negative differential resistance, whose occurrence and characteristics depend less on the presence or absence of defects.