Electronic and Optical Properties of Two-Dimensional Transition Metal Dichalcogenides
General Material Designation
[Thesis]
First Statement of Responsibility
Voshell, Andrew Bodhi
Subsequent Statement of Responsibility
Rana, Mukti
.PUBLICATION, DISTRIBUTION, ETC
Name of Publisher, Distributor, etc.
Delaware State University
Date of Publication, Distribution, etc.
2020
PHYSICAL DESCRIPTION
Specific Material Designation and Extent of Item
67
DISSERTATION (THESIS) NOTE
Dissertation or thesis details and type of degree
M.S.
Body granting the degree
Delaware State University
Text preceding or following the note
2020
SUMMARY OR ABSTRACT
Text of Note
Two dimensional (2D) materials have become a very popular topic in the last 15 years since the original isolation of graphene, which kickstarted a new class of ultra-thin materials with unique properties. Since then, many other layered materials were reduced to monolayer or few-layers, showing much different properties than their bulk form. Of these materials, transition metal dichalcogenides (TMD's) such as MoS2, WS2, and Mo1-xWxS2 have displayed different optical and electrical properties when reduced to a single layer, such as direct band gap transition compared to bulk indirect band gap. Furthermore, these materials show tunable qualities based on the thickness of the material, and are useful for optoelectronic devices. In this work, we investigated optical responses of monolayer MoS2, WS2, and Mo1-xWxS2 such as photoluminescence, absorption, and differential reflection, as well as thermal and substrate choice effects. The charge-transfer mechanics were investigated on germanium substrates and graphene/germanium heterostructures, in which we found a clear photoluminescence quenching effect of over 99% for WS2/graphene/Ge samples. The quenching mechanism of WS2 is clearly shown in germanium substrates, but has the potential to be useful in future optoelectronic systems that may require it.