Electron-beam-induced adatom-vacancy-complexes in mono- and bilayer phosphorene

TL;DR

This study investigates the creation, stability, and characteristics of defect complexes in mono- and bilayer phosphorene under electron irradiation, providing experimental data and simulations that enhance understanding of defect behavior for potential device applications.

Contribution

First experimental report of stable adatom-vacancy complexes in phosphorene, with detailed measurements and simulations of their formation and stability under electron irradiation.

Findings

Displacement cross section in bilayer phosphorene is 7.7 ± 1.4 barns.

Adatom-vacancy complexes can be stable for up to 68 seconds under irradiation.

Simulations suggest complexes should recombine easily, even in strained structures.

Abstract

Phosphorene, a puckered two-dimensional allotrope of phosphorus, has sparked considerable interest in recent years due to its potential especially for optoelectronic applications with its layer-number-dependant direct band gap and strongly bound excitons. However, detailed experimental characterization of its intrinsic defects as well as its defect creation characteristics under electron irradiation are scarce. Here, we report on the creation and stability of a variety of defect configurations under 60 kV electron irradiation in mono- and bilayer phosphorene including the first experimental reports of stable adatom-vacancy-complexes. Displacement cross section measurements in bilayer phosphorene yield a value of 7.7 +- 1.4 barn with an estimated lifetime of adatom-vacancy-complexes of 19.9 +- 0.7 s, while some are stable for up to 68 s under continuous electron irradiation. Surprisingly, ab initio-based simulations indicate that the complexes should readily recombine, even in structures strained by up to 3 %. The presented results will help to improve the understanding of the wide variety of defects in phosphorene, their creation, and their stability, which may enable new pathways for defect engineered phosphorene devices.