Mechanistic insights in phosphorene degradation

Abstract

The structural and chemical degradations of phosphorene severely limit its practical applications despite the enormous promise. In this regard, we investigate a cohort of microscopic kinetic mechanisms and develop a degradation phase diagram using first-principles calculations. At 400 K, the degradation and the competing self-annealing proceeds through the merger and annihilation of vacancies, respectively, which are triggered via itinerant vacancies and adatoms. A further increase in temperature beyond 650 K, the structural degradation results through the emission of the undercoordinated atoms from the defect and the concurrent pairwise sublimation. The role of interlayer vacancy diffusion is discarded in the context of structural degradation. The chemical degradation proceeds through the dissociation of an oxygen molecule that is activated at the room temperature on the pristine surface or spontaneous at the single-vacancy site. The present results are in agreement with the few available experimental conjectures and will motivate further efforts.