본문 바로가기 주메뉴 바로가기
국회도서관 홈으로 정보검색 소장정보 검색

목차보기

Title Page

Contents

ABSTRACT 12

초록 13

I. Introduction 14

II. Theory 16

A. Black Phosphorus 16

B. Raman Spectroscopy 18

C. Raman Spectrum of Black Phosphorus 21

III. Experiment 23

A. Sample Preparations 23

B. Polarized Optical Microscopy 24

C. HR-TEM Measurements 24

D. Polarized Raman measurements 25

E. Calculation of Enhancement Factors by Interference Effects 27

IV. Results 30

A. Electron and Optical Microscopy 30

B. Polarized Raman Spectroscopy 36

C. Polarization Dependence of Raman Modes for Different Excitation Wavelengths and Different Sample Thickness. 39

D. Interference effect 44

E. Few-Layer Black Phosphorus 50

V. Conclusions 57

VI. References 59

Figure II-1. (a) Atomic structure of BP. (b) side view. (c) top view. 16

Figure II-2. electronic band structure of (a) bulk, (b) monolayer, and (c) bilayer... 17

Figure II-3. Diagram of Raman scattering 19

Figure II-4. Example of diatomic crystal phonon dispersion. 20

Figure II-5. Schematic diagrams of phonon modes of BP. 21

Figure II-6. Raman spectrum of BP measured with the 514.5-㎚ excitation. 22

Figure III-1. Schematic of polarized low frequency micro-Raman set up. 26

Figure III-2. Schematic diagrams of multiple reflection interference in the absorption... 27

Figure IV-1. (a-d) Polarized optical microscope images of a BP crystal on TEM grid.... 31

Figure IV-2. Cross-polarized optical images of a BP crystal (thickness ~90 ㎚) on a... 32

Figure IV-3. Orientation dependence of color of a BP crystal on a SiO₂ /Si substrate in... 34

Figure IV-4. Orientation dependence of color of a BP crystal on slide glass in reflection... 34

Figure IV-5. Orientation dependence of color of a BP crystal on slide glass in... 35

Figure IV-6. (a) Crystal structure of BP. The principal axes are shown. (b) Polarized... 36

Figure IV-7. Polarization dependence of Raman modes for different excitation... 40

Figure IV-8. Polarization dependence of Raman modes in cross polarization. Each row... 41

Figure IV-9. Polarization dependence of Raman modes for different sample thickness.... 42

Figure IV-10. Raman spectra corresponding to data in Figure IV-9(e-p). The spectra are... 43

Figure IV-11. (a) Calculated interference enhancement factor as a function of the... 46

Figure IV-12. The wide-field Raman images for (a-d) Ag1, (e-h) Ag2, and (i-l) B2g...(이미지참조) 48

Figure IV-13. (a) Optical image of a sample with several BP flakes with different... 49

Figure IV-14. Few-layer BP sample image. 50

Figure IV-15. Spectra of 2,4 and 6 layer BP. 52

Figure IV-16. Polarization dependence of Raman peak intensities of few-layer BP for... 53

Figure IV-17. Polarization dependence of Raman peak intensities of few-layer BP for... 54

Figure IV-18. Polarization dependence of Raman peak intensities of few-layer BP for... 55

초록보기

본 연구에서는 흑린(black phosphorus) 시료를 다섯 종류의 파장을 사용하여 편광 라만 분광을 측정하였다. 시료의 결정 방향은 편광된 빛을 이용한 현미경과 고분해능 전자현미경을 통하여 확인하였다. 편광 라만 분광 측정 시, B2g 모드는 파장과 시료의 두께에 상관없이 일정한 편광 의존도를 보인다. 반면 Ag1과 Ag2 모드는 파장과 시료의 두께에 따라 특이한 편광 의존도를 보인다. 두께에 따른 변화는 흑린 시료의 복굴절과 이색성으로 인한 이방성 간섭 효과로 설명되지만, 파장에 따른 변화는 이 효과로 설명되지 않았다. 본 연구에서는 편광 라만 신호와 편광 현미경을 이용하여 흑린 시료의 결정 방향을 구분해 내는 방법을 제시 하고 있다.