Synthesis and characterization of Van Der Waals heterostructures, and nanofabrication of electronic devices based on two-dimensional materials

Date
2017-11
Advisor
Kasırga, Talip Serkan
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Bilkent University
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English
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Abstract

Last two decades have seen a phenomenal shift of the dimensionality paradigm in materials processing, from zero-dimensional nanoparticles and quantum dots to one-dimensional nanowires and nanotubes, to two-dimensional materials. Each above-mentioned category of the nanomaterial can be manipulated exclusively, and mentored to drive special properties. However, for each of them, it may take time to discover their true potential and proper application in contemporary technology. The emergence of graphene in 2004 triggered the scienti c community to turn their vision toward investigation of two-dimensional materials. The impact of the discovery of graphene with its rare characteristics was such huge that no subject had been studied in the past as much as two-dimensional materials have. Nowadays, there are brand new two-dimensional materials with more intriguing properties which no one could imagine. However, our current technology had developed based on bulk material, and it is not ready yet to accept the use of nanomaterials. Recent advances in nanoscale characterization opened up new opportunities for nanomaterials to be investigated so delicately. The other face of the discovery of nanomaterial is the need for ingenious fabrication method. Integration of electronic and optoelectronic circuits in con ned space is one of the top paid objectives in research and development. The goal is providing a faster computational speed, lower energy consumption, and reducing the size of these systems. Although this is a long-term plan, it is not farfetched once we connect the dots and think outside the box.Herein, we address synthesis, characterization, and manipulation of various two-dimensional materials. A thorough report on chemical vapor deposition of molybdenum disul de and tungsten diselenide is provided in this study. Besides this two material we encountered some anomalies in the behavior of an unknown two-dimensional material which we synthesized it in our lab. The next step is to establish novel methods in order to fabricate electronic devices supporting atomically-thin structures. We could formulate a straightforward method to assemble atomically thin ake of material on transmission electron microscope grid, compatible for microscopy of thin materials and adjustable for various characterization method including Raman spectroscopy, and atomic force microscopy. Last but not least, we introduced a novel method to induce mechanical strain on the two-dimensional ake. This method allows a dynamic scanning electron microscopy of the strained structure, which could be utilized for versatile applications. It worth to mention that, a fabrication process is mainly based on mentoring wet-transfer, focused ion beam, and electron beam lithography.

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Keywords
Two-Dimensional Material, Chemical Vapor Deposition, Physical Vapor Deposition, Electron Beam Lithography, Focused Ion Beam, Wet-Transfer and Manipulation Methods, Uniaxial-Strain Gauge
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Published Version (Please cite this version)