Open Access System for Information Sharing

Login Library

 

Thesis
Cited 0 time in webofscience Cited 0 time in scopus
Metadata Downloads

Angle-resolved photoemission study on Bi and Au intercalated epitaxial graphene

Title
Angle-resolved photoemission study on Bi and Au intercalated epitaxial graphene
Authors
손영섭
Date Issued
2021
Publisher
포항공과대학교
Abstract
Tuning the properties of graphene is a fundamental quest in the fields of both physics and applications. A potential way is to intercalate foreign atoms in between graphene and substrate. There have been many attempts to intercalate various atoms and molecules. However, crystal and electronic structures of such intercalate layers are difficult to probe by microscopy technique, and relatively little is known about intercalate layers compared to graphene. Because the property of graphene is tuned by the interactions between graphene and an intercalate layer, it is important to understand the nature of an intercalate layer. I studied epitaxial graphene on SiC(0001) intercalated by bismuth and gold atoms by means of angle-resolved photoemission spectroscopy. My research consists of three parts. Firstly, I reveal the electronic band structures of Bi-intercalated graphene. I identify two distinct phases depending on the coverage of intercalated atoms. One is metallic and the other is insulating. In metallic phase, the Bi-intercalate layer shows nearly-free electrons bands whose period follows SiC(0001)-(1 × 1). In insulating phase, the Bi-intercalate layer shows insulating flat bands with the period of SiC(0001)-(6√3×6√3)R30◦. Although the band structures of Bi are separated into two phases, the doping level of graphene varies continuously depending on the coverage of Bi atoms. Based on the electronic band structures and core-level spectra of Bi 5d level, I suggest a structural model for both phases of the Bi-intercalated graphene. Secondly, I revealed the electronic band structures of Au-intercalated graphene which is well known to have two phases. In the low coverage phase, in which graphene is n-doped, the intercalated layers shows insulating band structure with the period of SiC(0001)-(1 × 1). In the high coverage phase, in which graphene is p-doped, the intercalated layers shows metallic band structure with two kinds of periods. One is SiC(0001)-(1 × 1) and the other is similar with the Au(111) surface. Based on electronic band structures, I suggest a structural model for both phases of the Au-intercalated graphene. Lastly, I fabricate the chemical p-n junction of graphene in wafer-scale by introducing shadow mask. From the spatial scan of electronic band structures along the junction, I confirm the junction is abrupt in the scale of the beam size. Because the doping level of graphene is originated from the structure of the Au-intercalate layers, the p-n junction is expected to be abrupt in an atomic scale. The p-n junction fabricated by the proposed method may be useful for a fundamental study on atomically abrupt p-n junction of graphene.
URI
http://postech.dcollection.net/common/orgView/200000369287
https://oasis.postech.ac.kr/handle/2014.oak/111471
Article Type
Thesis
Files in This Item:
There are no files associated with this item.

qr_code

  • mendeley

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

Views & Downloads

Browse