  Transition metal dichalcogenides (TMDCs) have recently shown much promise as
thin layer semiconductors in application to transistor technology. TMDCs
provide a unique vantage point for studying the properties of phosphorene, a
highly efficient and tunable super-material. Phosphorene-TMDC heterostructure
nanodevices have remained largely unexplored due to the lack of air stability
observed in phosphorene under ambient conditions. This study investigates a
novel nanofabrication technique that effectively enhances the air stability and
practical scalability of graphene-analogous phosphorene. A phosphorene-WS2
heterostructure was first designed and synthesized via micromechanical
exfoliation and dry transfer methods. A novel umbrella contact was fabricated
using electron beam lithography which extended the electrical anode over the
phosphorene heterojunction region. SEM, Raman spectroscopy, gate transport, and
photocurrent response techniques were employed to characterize the device
physically and electronically. Devices fabricated with an extended anodic
contact remained functional for extended periods of time, suggesting that the
contact had prevented the phosphorene from degradation in ambient conditions.
Preliminary results obtained via current response indicate a promising
heterojunction with high speed transistor properties. This work suggests the
unprecedented longevity and practical scalability of phosphorene utilizing a
novel contact nanofabrication technique. Potential applications of the
nanodevice include next generation electronic devices, photodetectors, energy
storage devices, and photovoltaic cells.
