Dynamics and Mechanisms of Exfoliated Black Phosphorus Sublimation.
We report on real time observations of the sublimation of exfoliated black phosphorus layers throughout annealing using in situ low energy electron microscopy. We found that sublimation manifests itself above 375 ± 20 °C through the nucleation and expansion of asymmetric, faceted holes with the long axis aligned along the [100] direction and sharp tips defined by edges consisting of alternating (10) and (11) steps. This thermally activated process repeats itself via successive sublimation of individual layers. Calculations and simulations using density functional theory and kinetic Monte Carlo allowed to determine the involved atomic pathways. Sublimation is found to occur via detachments of phosphorus dimers rather than single atoms. This behavior and the role of defects is described using an analytical model that captures all essential features. This work establishes an atomistic-level understanding of the thermal stability of exfoliated black phosphorus and defines the temperature window available for material and device processing.
Department of Engineering Physics, École Polytechnique de Montréal , C. P. 6079, Succursale Centre-Ville, Montréal, Québec H3C 3A7, Canada.
Matthieu
M
Fortin-Deschênes
Département de Chimie, Université de Montréal , 2900 Boulevard Edouard Montpetit, Montréal, Québec H3T 1J4, Canada.
Pierre L
PL
Levesque
Département de Chimie, Université de Montréal , 2900 Boulevard Edouard Montpetit, Montréal, Québec H3T 1J4, Canada.
Richard
R
Martel
Department of Engineering Physics, École Polytechnique de Montréal , C. P. 6079, Succursale Centre-Ville, Montréal, Québec H3C 3A7, Canada.
Oussama
O
Moutanabbir