Temporal and Thermal Stability of Al2O3-Passivated Phosphorene MOSFETs

This letter evaluates temporal and thermal stability of a state-of-the-art few-layer phosphorene MOSFET with Al₂O₃ surface passivation and Ti/Au top gate. As fabricated, the phosphorene MOSFET was stable in atmosphere for at least 100 h. With annealing at 200 °C in dry nitrogen for 1 h, its drain current increased by an order of magnitude to ~100 mA/mm, which could be attributed to the reduction of trapped charge in Al₂O₃ and/or Schottky barrier at the source and drain contacts. Thereafter, the drain current was stable between -50°C and 150°C up to at least 2000 h. These promising results suggest that environmental protection of phosphorene should not be a major concern, and passivation of phosphorene should focus on its effect on electronic control and transport as in conventional silicon MOSFETs. With cutoff frequencies approaching the gigahertz range, the present phosphorene MOSFET, although far from being optimized, can meet the speed and stability requirements of most flexible electronics for which phosphorene is intrinsically advantageous due to its corrugated lattice structure.