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Synthesis, Characterization and Processing of Exotic 2D Materials Beyond Graphene via Chemical Vapor Deposition Techniques

  • Author(s): Ionescu, Robert
  • Advisor(s): Ozkan, Cengiz S
  • et al.
Abstract

Over the last decade, since the introduction of graphene in 2004, 2D materials have become a very hot topic. Excellent chemical and mechanical stability along with incredible transport carrier properties, graphene has sparked interest in other 2D materials. Graphene has a portfolio of applications but, lack of a band gap hinders its potential in semiconductor applications which has pushed researcher to look at more exotic 2D materials with semiconductor properties. This new class of 2D semiconductors under the form of MX2 which is composed or a transition metal and a chalcogen atom. Mobility is good for low energy loss transmission of electrons from one point to another and is an important aspect in electronics and optoelectronics which apply to conductivity and light absorption. In conductors usually we have an overlap of the valence and conduction band where electrons move freely on the other side of the spectrum we have insulators where the gap between the valence and conduction band are too large to feasible transition between to allow for conductivity. Semiconductor are located in between these two extremes with enough gap where electrons only require a small amount of energy for them to move from one side to another. This concept is very important when talking about light interactions and absorption. In order for these devices to be feasible we need band gap to exist in the spectrum of visible light. Semiconductors have a high and low resistance states which has an on/off ration making a semiconductor of interest in many applications such as transistors and photodetectors. Direct bang gap in photodetector rely on transfer of photons and we can achieve this by using monolayer semiconductor materials. In order to be able to obtain all these properties we would have to be able to synthesize all these new 2D materials in the first place. In this work synthesis methods were studied to try to understand these materials and achieve large area growth. First we start with powered growth of novel semiconductor materials and move to a scalable liquid technique that is potentially able achieve wafer scale growth.

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