Title

Band Structure Engineering for Optimal Optoelectronic Device

Alternative Title

광전자소자 최적화를 위한 밴드 구조 엔지니어링

DGIST Authors

Sang-Hyeon Lee ; Jong-Soo Lee ; Youngwook Kim

Advisor

이종수

Co-Advisor(s)

Youngwook Kim

Issued Date

2026

Awarded Date

2026-08-01

Type

Thesis

Description

2D materials, Optoelectric device, Low-dimensional materials, Tunneling device, Computational Spectrometer, Defect engineering

Table Of Contents

List of Contents

Abstract i
List of contents ii
List of figures iv

1. Introduction
1.1 Two-Dimensional Material 1
1.1.1 Introduction to of Two-Dimensional Materials1
1.1.2 Fundamental Properties of Two-Dimensional Materials 5
1.2 Heterostructure9
1.2.1 Concept of Heterojunctions 9
1.2.2 2D/2D Heterostructure 13
1.2.3 Characterization and Analysis of 2D Heterostructures 17
1.3 Fabrication of 2D Heterostructures 23
1.3.1 Synthesis and Preparation of 2D materials 24
1.3.2 Transfer and Stacking of 2D layers 26
1.3.3 Electrode Formation and Contact Engineering 28
1.4 Characterization of Photodetector 29
1.4.1 Electrical Characterization 30
1.4.2 Optical Characterization 31
1.4.3 Figures of Merit and Performance Parameters 32
2. Floating-Base Bipolar Junction (FBBJ): Gated Electrostatic Band Modulation
2.1 Introduction 35
2.2 Experimental section 38
2.3 Result and Discussion 41
2.3.1 Overview of a Floating—Base Bipolar Junction phototransistor 41
2.3.2 Electrostatic Doping—Induced Band Structure Analysis of FBBJ 44
2.3.3 Tunable photoresponse mediated by interfacial barrier—matching transition 53
2.3.4 Electrostatic Doping-Induced Spectral Response and Computational Spectrometer of
the FBBJ Device 62
2.4 Conclusion 66
3. WSe2/h-BN/CdSe QD/Graphene Tunneling Photodetector: Interfacial Barrier Engineering
3.1 Introduction 68
3.2 Result and discussion 70
3.2.1 Device Structure and Materials 70
3.2.2 In-depth analysis and understanding of the tunneling phenomena 75
3.2.3 Optical property for validating the tunneling 81
3.2.4 Photodetector application 87
3.4 Conclusion 91
4. Ion-Beam-Doped WSe2 Homojunction: Intrinsic Band Engineering via Controlled Doping
4.1 Introduction 92
4.2 Result and Discussion 96
4.2.1 Device Fabrication Process 96
4.2.2 Defect Characterization of Ion-Beam-Treated WSe2 97
3.2.3 Transport Characteristics of the Ion-Beam-Induced Lateral p–n Junction· 101
4.2.4 Photodetector application 104
4.3 Conclusion 108

URI

https://scholar.dgist.ac.kr/handle/20.500.11750/60741
http://dgist.dcollection.net/common/orgView/200001006998

DOI

10.22677/THESIS.200001006998

Degree

Doctor

Department

Department of Energy Science and Engineering

Publisher

DGIST

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