Layer Dependence of Dielectric Response and Water-Enhanced Ambient Degradation of Highly Anisotropic Black As

Abstract

Black arsenic (BAs) is a van der Waals layered material with a puckered honeycomb structure and has received increased interest due to its anisotropic properties and promising performance in devices. Here, crystalline structure, thickness-dependent dielectric responses, and ambient stability of BAs nanosheets are investigated using STEM imaging and spectroscopy. Atomic-resolution HAADF-STEM images directly visualize the three-dimensional structure and evaluates the degree of anisotropy. STEM-EELS is used to measure the dielectric response of BAs as a function of the number of layers. Finally, BAs degradation under different ambient environments is studied highlighting high sensitivity to moisture in the air.

2D Arsenene and Arsenic Materials: Fundamental Properties, Preparation, and Applications

“…Black arsenic also undergoes considerable structural destruction in several days, but its rate of degradation is relatively slow compared with that of gray arsenic, which occurs in a few hours. [ 65 ] In particular, black arsenic shows a loss of arsenic elements and no accumulation of arsenic oxide after ambient air exposure (Figure 5c). Yun et al emphasized the effect of humidity on black arsenic nanoflakes, speculating that volatile products formed through the interaction between arsenic and water vapor in air.…”

“…Yun et al emphasized the effect of humidity on black arsenic nanoflakes, speculating that volatile products formed through the interaction between arsenic and water vapor in air. [ 65 ] Figure a,b compares the compositions of black arsenic flakes stored in humid air, dry air, and dry vacuum to investigate degradation in detail. The degradation of most regions of black arsenic flakes occurred in just 2 days, while no obvious degradation was observed in dry air (humidity of ≈2.5%).…”

“…Systematic studies on the stability of black arsenic confirmed that oxygen alone in air does not react with black arsenic and highlighted the high sensitivity of black arsenic toward steam in air. [ 65 ]…”

“…Reproduced with permission. [ 65 ] Copyright 2020, American Chemical Society. c) Raman spectra of freshly prepared gray arsenic nanoflakes after 10 days of storage in DMSO.…”

“…[ 38 ] Moreover, Yun et al purchased commercial black arsenic crystals prepared by a chemical vapor transport technique using arsenic as a precursor from 2D Semiconductors Inc. [ 65 ] Then, 2D black arsenic nanoflakes were also successfully exfoliated from bulk black arsenic crystals using Scotch tape (Figure 9c). [ 65 ]…”