69 research outputs found
Broadband Linear-Dichroic Photodetector in a Black Phosphorus Vertical p-n Junction
The ability to detect light over a broad spectral range is central for
practical optoelectronic applications, and has been successfully demonstrated
with photodetectors of two-dimensional layered crystals such as graphene and
MoS2. However, polarization sensitivity within such a photodetector remains
elusive. Here we demonstrate a linear-dichroic broadband photodetector with
layered black phosphorus transistors, using the strong intrinsic linear
dichroism arising from the in-plane optical anisotropy with respect to the
atom-buckled direction, which is polarization sensitive over a broad bandwidth
from 400 nm to 3750 nm. Especially, a perpendicular build-in electric field
induced by gating in black phosphorus transistors can spatially separate the
photo-generated electrons and holes in the channel, effectively reducing their
recombination rate, and thus enhancing the efficiency and performance for
linear dichroism photodetection. This provides new functionality using
anisotropic layered black phosphorus, thereby enabling novel optical and
optoelectronic device applications.Comment: 18 pages, 5 figures in Nature Nanotechnology 201
Optical Properties of Noble Metal Nanoparticles in Dielectric Thin Films
(Statement of Responsibility) by Robin Jacobs-Gedrim(Thesis) Thesis (B.A.) -- New College of Florida, 2010(Electronic Access) RESTRICTED TO NCF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE(Bibliography) Includes bibliographical references.(Source of Description) This bibliographic record is available under the Creative Commons CC0 public domain dedication. The New College of Florida, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.(Local) Faculty Sponsor: Sendova, Marian
Scalable synthesis of two-dimensional antimony telluride nanoplates down to a single quintuple layer
Rapid optical determination of topological insulator nanoplate thickness and oxidation
The stability of 2D antimony telluride (Sb2Te3) nanoplates in ambient conditions is elucidated. These materials exhibit an anisotropic oxidation mode, and CVD synthesized samples oxidize at a much faster rate than exfoliated samples investigated in previous studies. Optical measurement techniques are introduced to rapidly measure the oxidation modes and thickness of 2D materials. Auger characterization were conducted to confirm that oxygen replaces tellurium as opposed to antimony under ambient conditions. No surface morphology evolution was detected in AFM before and after exposure to air. These techniques were employed to determine the origin of the thickness dependent color change effect in Sb2Te3. It is concluded that this effect is a combination of refractive index change due to oxidation and Fresnel effects
Defect-Induced Photoluminescence in Monolayer Semiconducting Transition Metal Dichalcogenides
It is well established that defects strongly influence properties in two-dimensional materials. For graphene, atomic defects activate the Raman-active centrosymmetric A<sub>1g</sub> ring-breathing mode known as the D-peak. The relative intensity of this D-peak compared to the G-band peak is the most widely accepted measure of the quality of graphene films. However, no such metric exists for monolayer semiconducting transition metal dichalcogenides such as WS<sub>2</sub> or MoS<sub>2</sub>. Here we intentionally create atomic-scale defects in the hexagonal lattice of pristine WS<sub>2</sub> and MoS<sub>2</sub> monolayers using plasma treatments and study the evolution of their Raman and photoluminescence spectra. High-resolution transmission electron microscopy confirms plasma-induced creation of atomic-scale point defects in the monolayer sheets. We find that while the Raman spectra of semiconducting transition metal dichalcogenides (at 532 nm excitation) are insensitive to defects, their photoluminescence reveals a distinct defect-related spectral feature located ā¼0.1 eV below the neutral free A-exciton peak. This peak originates from defect-bound neutral excitons and intensifies as the two-dimensional (2D) sheet is made more defective. This spectral feature is observable in air under ambient conditions (room temperature and atmospheric pressure), which allows for a relatively simple way to determine the defectiveness of 2D semiconducting nanosheets. Controlled defect creation could also enable tailoring of the optical properties of these materials in optoelectronic device applications
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