Bias dependent transport property of defective phosphorene.

\textbf{Phosphorene is receiving great research interests because of its peculiar physical properties.} \textbf{Nonetheless, no systematic studies on the transport properties modified due to defects have been} \textbf{performed. Here, we present the electronic band structure, defect formation energy and bias} \textbf{dependent transport property of various defective systems. We found that the defect formation} \textbf{energy is much less than that in graphene. The defect configuration strongly affects the electronic} \textbf{structure. The band gap vanishes in single vacancy layers, but the band gap reappears in divacancy} \textbf{layers. Interestingly, a single vacancy defect behaves like a p-type impurity for transport property.} \textbf{Unlike the common belief, we observe that the vacancy defect can contribute to greatly increasing} \textbf{the current. Along the zigzag direction, the current in the most stable single vacancy structure was} \textbf{significantly increased as compared with that found in the pristine layer. In addition, the current} \textbf{along the armchair direction was always greater than along the zigzag direction and we observed a} \textbf{strong anisotropic current ratio of armchair to zigzag direction.}