4 research outputs found
Metal Oxide Nanoparticle Growth on Graphene via Chemical Activation with Atomic Oxygen
Chemically interfacing the inert
basal plane of graphene with other
materials has limited the development of graphene-based catalysts,
composite materials, and devices. Here, we overcome this limitation
by chemically activating epitaxial graphene on SiC(0001) using atomic
oxygen. Atomic oxygen produces epoxide groups on graphene, which act
as reactive nucleation sites for zinc oxide nanoparticle growth using
the atomic layer deposition precursor diethyl zinc. In particular,
exposure of epoxidized graphene to diethyl zinc abstracts oxygen,
creating mobile species that diffuse on the surface to form metal
oxide clusters. This mechanism is corroborated with a combination
of scanning probe microscopy, Raman spectroscopy, and density functional
theory and can likely be generalized to a wide variety of related
surface reactions on graphene
Reconnaissance et synthese vocale dans les telecommunications
SIGLECNRS-CDST / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc
Rapid and Large-Area Characterization of Exfoliated Black Phosphorus Using Third-Harmonic Generation Microscopy
Black phosphorus
(BP) is a layered semiconductor that recently
has been the subject of intense research due to its novel electrical
and optical properties, which compare favorably to those of graphene
and the transition metal dichalcogenides. In particular, BP has a
direct bandgap that is thickness-dependent and highly anisotropic,
making BP an interesting material for nanoscale optical and optoelectronic
applications. Here, we present a study of the anisotropic third-harmonic
generation (THG) in exfoliated BP using a fast scanning multiphoton
characterization method. We find that the anisotropic THG arises directly
from the crystal structure of BP. We calculate the effective third-order
susceptibility of BP to be ∼1.64 × 10<sup>–19</sup> m<sup>2</sup> V<sup>–2</sup>. Further, we demonstrate that
multiphoton microscopy can be used for rapid, large-area characterization
indexing of the crystallographic orientations of many exfoliated BP
flakes from one set of multiphoton images. This method is therefore
beneficial for samples of areas ∼1 cm<sup>2</sup> in future
investigations of the properties and growth of BP
Rapid and Large-Area Characterization of Exfoliated Black Phosphorus Using Third-Harmonic Generation Microscopy
Black phosphorus
(BP) is a layered semiconductor that recently
has been the subject of intense research due to its novel electrical
and optical properties, which compare favorably to those of graphene
and the transition metal dichalcogenides. In particular, BP has a
direct bandgap that is thickness-dependent and highly anisotropic,
making BP an interesting material for nanoscale optical and optoelectronic
applications. Here, we present a study of the anisotropic third-harmonic
generation (THG) in exfoliated BP using a fast scanning multiphoton
characterization method. We find that the anisotropic THG arises directly
from the crystal structure of BP. We calculate the effective third-order
susceptibility of BP to be ∼1.64 × 10<sup>–19</sup> m<sup>2</sup> V<sup>–2</sup>. Further, we demonstrate that
multiphoton microscopy can be used for rapid, large-area characterization
indexing of the crystallographic orientations of many exfoliated BP
flakes from one set of multiphoton images. This method is therefore
beneficial for samples of areas ∼1 cm<sup>2</sup> in future
investigations of the properties and growth of BP