CVD GROWTH and CHARACTERIZATION OF 2D TRANSITION METAL DICHALCOGENIDES, MoS2 and WS2

Year 2017, Volume: 18 Issue: 2, 375 - 387, 30.06.2017

Nihan Kosku Perkgöz

https://doi.org/10.18038/aubtda.303258

Cited By: 4

Abstract

Two-dimensional
transition metal dichalcogenides (TMDC), specifically molybdenum disulfide and tungsten
disulfide have received significant attention as their direct bandgap exhibits
a shift from indirect to direct as the layer goes to single molecular thickness
(2D). Hence, they have high potential to pave way for novel optoelectronic
devices. However, their structural and optical properties are still not
completely understood, especially, spatial change of photoluminescence
intensities, variations in excitons-trions, and shift in peak wavelengths in
these 2D flake structures need further investigation. In this research work, after
growing TMDCs using chemical vapor deposition technique, in addition to
measuring micro Raman and photoluminescence spectra, we performed dark field
microscopy measurements and photoluminescence mappings to identify grain
boundaries and seeding particles. The results clearly show that the flakes,
which look lie single-piece through the optical spectroscopy images, in fact,
include grain boundaries, seeds and wrinkles. Photoluminescence maps reveal
that emission occurs due to different mechanisms such as excitons and trions,
depending on the locations on the flakes where the measurement is performed. Our
results show that there are different routes that emission can occur and 2D
TMDCs provide a rich variety of alternatives to realize novel photonic devices. 

Keywords

MoS2, WS2, two-dimensional materials, chemical vapor deposition

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