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dc.contributor.advisorZhang, Xixiang
dc.contributor.authorChiu, Ming-Hui
dc.date.accessioned2018-05-16T13:42:28Z
dc.date.available2018-05-16T00:00:00Z
dc.date.issued2018-05-09
dc.identifier.citationChiu, M.-H. (2018). Band Alignment Determination of Two-Dimensional Heterojunctions and Their Electronic Applications. KAUST Research Repository. https://doi.org/10.25781/KAUST-Z4B06
dc.identifier.doi10.25781/KAUST-Z4B06
dc.identifier.urihttp://hdl.handle.net/10754/627889
dc.description.abstractTwo-dimensional (2D) layered materials such as MoS2 have been recognized as high on-off ratio semiconductors which are promising candidates for electronic and optoelectronic devices. In addition to the use of individual 2D materials, the accelerated field of 2D heterostructures enables even greater functionalities. Device designs differ, and they are strongly controlled by the electronic band alignment. For example, photovoltaic cells require type II heterostructures for light harvesting, and light-emitting diodes benefit from multiple quantum wells with the type I band alignment for high emission efficiency. The vertical tunneling field-effect transistor for next-generation electronics depends on nearly broken-gap band alignment for boosting its performance. To tailor these 2D layered materials toward possible future applications, the understanding of 2D heterostructure band alignment becomes critically important. In the first part of this thesis, we discuss the band alignment of 2D heterostructures. To do so, we firstly study the interlayer coupling between two dissimilar 2D materials. We conclude that a post-anneal process could enhance the interlayer coupling of as-transferred 2D heterostructures, and heterostructural stacking imposes similar symmetry changes as homostructural stacking. Later, we precisely determine the quasi particle bandgap and band alignment of the MoS2/WSe2 heterostructure by using scan tunneling microscopy/spectroscopy (STM/S) and micron-beam X-ray photoelectron spectroscopy (μ-XPS) techniques. Lastly, we prove that the band alignment of 2D heterojunctions can be accurately predicted by Anderson’s model, which has previously failed to predict conventional bulk heterostructures. In the second part of this thesis, we develop a new Chemical Vapor Deposition (CVD) method capable of precisely controlling the growth area of p- and n-type transition metal dichalcogenides (TMDCs) and further form lateral or vertical 2D heterostructures. This method also allows p- and n-type TMDCs to separately grow in a selective area in one step. In addition, we demonstrate a first bottom-up 2D complementary inverter based on hetero-TMDCs.
dc.language.isoen
dc.subjectBand Alignment
dc.subject2D Materials
dc.subjectHeterojunction
dc.subjectTransition metal dichalcogenide
dc.subjectWSe2
dc.titleBand Alignment Determination of Two-Dimensional Heterojunctions and Their Electronic Applications
dc.typeDissertation
dc.contributor.departmentPhysical Science and Engineering (PSE) Division
dc.rights.embargodate2018-05-16
thesis.degree.grantorKing Abdullah University of Science and Technology
dc.contributor.committeememberLi, Lain-Jong
dc.contributor.committeememberHe, Jr-Hau
dc.contributor.committeememberAnthopoulos, Thomas D.
thesis.degree.disciplineMaterials Science and Engineering
thesis.degree.nameDoctor of Philosophy
dc.rights.accessrightsAt the time of archiving, the student author of this dissertation opted to temporarily restrict access to it. The full text of this dissertation became available to the public after the expiration of the embargo on 2018-05-16.
refterms.dateFOA2018-05-16T00:00:00Z


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