Title Page

Contents

ABSTRACT 10

Chapter 1. Introduction 14

1.1. Overview of two-dimensional van der Waals multilayer 14

1.2. Contact resistance and method of two-dimensional multilayer field-effect transistor 15

1.3. Channel migration and charge scattering mechanism in two-dimensional multilayers 17

Chapter 2. Experiments and analysis method 18

2.1. Current-Voltage measurement 18

2.2. Transfer length method 20

2.3. Four-probe measurement 22

2.4. Y-function method 23

Chapter 3. Enhanced Interlayer Charge Injection Efficiency in van der Waals Multilayers via Vertical Double-Side Contacts (VDC) 25

3.1. Introduction 25

3.2. Electrical characterization via VDC 26

3.2.1. Device fabrication 26

3.2.2. Measurement method of TC, BC, and VDC 28

3.2.3. Output and transfer characteristics in comparison with TC, BC, and VDC 30

3.3. Contact characteristics via VDC 34

3.4. The effectiveness of VDC 38

3.5. Conclusion 40

Chapter 4. Contact-structure-dependent conducting channel migration in two-dimensional multilayer field-effect transistor 41

4.1. Introduction 41

4.2. Experimental details 43

4.2.1. Device fabrication 43

4.2.2. Optical and Electrical Characterization 43

4.3. Channel migration in 2D multilayer FET 45

4.4. Four-probe measurement via VDC 47

4.5. Channel migration mechanism in 2D multilayer 50

4.6. Conclusion 52

Chapter 5. Carrier scattering mechanisms at high temperature in multilayer rhenium disulfide field-effect transistor 53

5.1. Introduction 53

5.2. Device fabrication 54

5.3. Electrical characterization of 2D FET in high temperature 56

5.3.1. Output characteristics and contact properties 56

5.3.2. Transfer characteristics 60

5.4. Temperature-dependent field-effect mobility 63

5.5. Conclusion 66

Chapter 6. Conclusion 67

Reference 68

ABSTRACT IN KOREAN 72

Figure 2.1. Transfer and transconductance curve and the method to extract flat-band voltage for top and bottom channel. 19

Figure 2.2. Transfer length method (TLM) structure and method channel. 21

Figure 2.3. Schematic configuration for four-probe measurement and Y-function method (YFM). 24

Figure 3.1. Device information of vertical double-side contact (VDC) and optical Raman property of two-dimensional (2D) multilayer rhenium... 27

Figure 3.2. Illustration for the current flow scheme under different contact configuration with top contact (TC), bottom contact (BC), and vertical double-... 29

Figure 3.3. Output (ID-VD) characteristics in comparison with TC, BC, VDC, and TC+BC.[이미지참조] 31

Figure 3.4. Electrical properties of 2D multilayer ReS₂. 33

Figure 3.5. TLM analysis for 2D multilayer ReS₂ FET. 36

Figure 3.6. Comparison of contact resistance. 37

Figure 3.7. Effectiveness of the use of VDC for various 2D materials. 39

Figure 3.8. Effectiveness of the use of VDC for 2D multilayers as a function of tReS₂.[이미지참조] 39

Figure 4.1. Device information and optical Raman property of 2D multilayer tungsten diselenide (WSe₂). 44

Figure 4.2. Transfer (ID-VG) curves, transconductance (gm) curves, and second derivative (dgm) curves in each contact configurations: TC, BC, and...[이미지참조] 46

Figure 4.3. Four-probe measurement via VDC and channel resistance. 49

Figure 4.4. Schematic diagram of conducting channel migration mechanism 51

Figure 5.1. Device information of fabricated multilayer ReS₂ FET. 55

Figure 5.2. Output characteristics and contact properties. 59

Figure 5.3. Transfer characteristics at each temperature. 62

Figure 5.4. Temperature-dependent field-effect mobility. 65