Design and Microscopic Investigation of the Growth and Electronic Structure of Low-dimensional Heterointerfaces PDF Download

Author: Dong, Xi
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 163

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Book Description
In the quickly advancing world of material synthesis and processing, finer gauges are being developed for controlling dimensionality and constitutions of the materials. Apart from their bulk counterparts, remarkable physics has been demonstrated with the reduction of dimensionality, such as creation of zero-dimensional quantum dots with designed bandgap, one-dimensional (1D) nanotubes with excellent thermal and electrical conductivity and two-dimensional (2D) monolayer with direct bandgap, etc. Furthermore, incorporations of these materials into heterostructures (HSs) by bringing dissimilar constituents together, not only offers an opportunity to tune the structure and strength of the existing electronic properties of each constituent, but also of the capacity to generate novel electronic properties. Understanding the interfacial interactions holds a crucial role in tackling the origins of these changes which creates a strong desire for controlled synthesis of HSs and local investigation of the interfacial phenomenon. In the low-dimensional (LD) solid-state systems, depending on the configurations of the HSs (lateral or vertical), interfacial phenomenon that is confined within a few atomic layers, or a few atoms/molecules are readily available for probing by surface-sensitive techniques due to their limited sizes. To properly interpretate the origins of morphological alterations and electronic perturbations in a HS, both high-quality samples and microscopic characterization tools are required. Sample quality must be controlled to reduce the unintentional modification of the sample property. For that, molecular beam epitaxy (MBE) and organic molecular beam epitaxy (OMBE) are employed in our studies. They have excellent control on the growth parameters that fine tune the growth rate and growth kinetics. They can deposit high-quality thin films with sub-monolayer precision and create HSs from sequential depositions. Later, high-resolution scanning tunneling microscopy/spectroscopy (STM/STS) is utilized to connect the dots between the atomically resolved local morphology and the electronic structure perturbation which improves our understanding of the interfacial phenomenon. In this dissertation, we will investigate various HSs constructed with inorganic and organic thin films to demonstrate the crucial importance of the interfacial effect in tuning, selecting, and creating of the desired electronic structures in the LD systems. Different phase engineering and property tunning techniques will be revealed and connected to the interfacial influence by our selected studies. The first study will focus on probing the thin film growth morphology from tunning the strength of the interfacial interaction with the substrate. The second study will explore a new technique that incorporate the phase transition with the 2D lateral core-shell HSs construction which creates an interesting topological insulator and superconductor pair for future investigation. The third study will investigate an organic charge transfer complex HS, which offers more microscopic evidence for the macroscopic phase transition in bulk. Better understanding of the interfacial effect from our studies could contribute to the logical choice of the constituents for the HS construction and rational modification of the substrate interactions for high-quality thin film growth. In the last study, we will employ the knowledge of previous studies and aim to create a high-quality HS system which induces superconductivity in a semiconductor thin film.