Evaluation of Flexible Resistive Random Access Memory Devices Fabricated with Nanocomposites of 2D Materials
- Abstract
- In this study, 2D materials and their nanocomposites have been explored as the functional layer of resistive random access memory (RRAM) devices. 2D materials and their nanocomposites such as molybdenum disulfide-polyvinyl alcohol (MoS_2-PVA), hexagonal boron nitride flakes-MoS2 quantum dots (hBN-MoS_2QDs), flakes of tungsten disulfide (WS_2) and hBN flakes-graphene quantum dots (hBN-GQDs) have been sandwiched between two metallic electrodes to complete the simple structure of RRAM devices. All-Printed technology was used to fabricate each RRAM device on a flexible and transparent substrate. All the devices displayed highly stable, repeatable and bipolar resistive switching characteristics. The least switching ratio was shown by the active layer of MoS2-PVA (1.28x10^2) while hBN-MoS_2QDs, WS_2 and hBN-GQDs exhibited a superior value of 10^3 each. Lowest retention time of 10^4 s was exhibited by the WS_2 flakes while MoS_2-PVA, hBN-MoS_2QDs, and hBN-GQDs showed a higher value of 10^5 s each. All 2D materials based flexible RRAM devices were tested for their bendability in the bending diameter range of 500 mm to 2 mm. Functional layer of MoS_2-PVA showed maximum number of bending cycles (2000 cycles) without any prominent decay in the device performance while hBN-MoS_2QDs, WS_2 flakes and hBN-GQDs exhibited mechanical robustness upto 1500 cycles each respectively. Conduction mechanism shown by active layers of MoS_2-PVA and WS_2 flakes was space charge limited current (SCLC) while conductive filaments were formed in the active layer of hBN-GQDs and hBN-MoS_2QDs. Furthermore, functional thin films of hBN-GQDs and WS_2 flakes were also encapsulated with atomically thin film of aluminum oxide (Al_2O_3) through spatial atmospheric atomic layer deposition (SAALD) system to enhance their lifetime. These obtained results clearly illustrate that functional layers based on 2D materials have a huge potential to replace the existing nanomaterials used as active layers of RRAM devices.
- Issued Date
- 2018
- Awarded Date
- 2018. 2
- Type
- Dissertation
- Alternative Author(s)
- Rehman, Muhammad Muqeet
- Affiliation
- 제주대학교 일반대학원
- Department
- 대학원 메카트로닉스공학과
- Advisor
- 최경현
- Table Of Contents
- Abstract xiii
1. Introduction 1
1.1 Two Dimensional Materials 1
1.2 Role of 2D Materials in RRAM Devices 3
1.2.1 Graphene and its Nanocomposites 3
1.2.2 MoS_2 and its Nanocomposites 4
1.2.3 Other 2D Materials and their Nanocomposites 4
1.3 Printing Technologies 5
1.3.1 Reverse Offset Electrode Patterning 5
1.3.2 Electrohydrodynamic Patterning and Atomization 7
1.3.3 Reciprocating Inkjet Head for Electrode Patterning 8
1.3.4 Electrohydrodynamic Atomization for Thin Film Deposition 10
2 Experimental 11
2.1 Synthesis of functional materials 11
2.1.1 Synthesis of WS_2 flakes 11
2.1.2 Synthesis of MoS_2 flakes blended with PVA 13
2.1.3 Synthesis of hBN flakes blended with GQDs 14
2.1.4 Synthesis of hBN flakes blended with MoS_2QDs 17
2.2 Surface Characterizations 18
2.2.1 Surface Morphology 18
2.2.2 Compositional Characterization 22
2.2.3 Optical Characterization 25
2.2 Fabrication of flexible RRAM devices 27
2.2.1 Fabrication of Ag/WS_2/Ag RRAM 27
2.2.2 Fabrication of Ag/hBN-GQDs/Ag RRAM 31
2.2.3 Fabrication of ITO/hBN-MoS_2QDs/Ag RRAM 36
2.2.4 Fabrication of Ag/MoS_2-PVA/Ag RRAM 39
3 Resistive switching in as synthesized 2D materials and their nanocomposites 43
3.1 Flexible Ag/WS_2/Ag RRAM 43
3.1.1 Electrical Characterization 43
3.1.2 Conduction Mechanism 46
3.1.3 Mechanical Characterization 48
3.2 Flexible Ag/hBN-GQDs/Ag RRAM 49
3.2.1 Electrical Characterization 49
3.2.2 Conduction Mechanism 52
3.2.3 Mechanical Characterization 55
3.3 Flexible ITO/hBN-MoS_2QDs/Ag RRAM 57
3.3.1 Electrical Characterization 57
3.3.2 Conduction Mechanism 60
3.3.3 Mechanical Characterization 63
3.4 Flexible Ag/MoS_2-PVA/Ag RRAM 66
3.4.1 Electrical Characterization 66
3.4.2 Conduction Mechanism 68
3.4.3 Mechanical Characterization 72
4. Conclusions and Future work 75
4.1 Conclusions 75
4.2 Future work 75
References 77
- Degree
- Doctor
- Publisher
- 제주대학교 일반대학원
- Citation
- 레흐만무하마드무키트. (2018). Evaluation of Flexible Resistive Random Access Memory Devices Fabricated with Nanocomposites of 2D Materials
- Appears in Collections:
- Faculty of Applied Energy System > Mechatronics Engineering
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