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Development of Intrinsic Self-Powered Photodetectors based on Piezo-Phototronic Effect

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Abstract
나노 장치 / 센서의 개발을 위한 나노 기술의 적용 및 활용은 전자, 통신, 광학, 의료 및 국방 기술 분야의 차세대 시스템을 구축하는데 필요한 기반 기술중의 하나이다. 또한, 초소형의 나노 시스템이 배터리나 다른 전원공급 없이 자가발전과 동시에 작동하는 것은 매우 진전된 과학 기술의 발전에 해당한다. 광전자의 관점에서는 외부 바이어스 전압/배터리 / 전원공급 없이 작동하는 자가발전 광 검출기를 구성하는 것은 무선 및 독립적 감지 장치의 개발을 위하여 필요한 중요한 요소기 술이다. 따라서, 본 연구에서는 광 검출기 (Photo Detector, PD)의 자가구동 전원의 역할을 할수 있는 압전 나노 발전기 (Piezo-electric Nanogenerator, PNG)의 개발을 시도하였다. PNG는 변형에 반응하는 비대칭성 물질의 압전 전위의 발생을 구동력으로 활용한다. 또한, 압전 재료의 전위에 의해서 유도된 변형은 피에조트로닉스를 기반으로 하는 금속–반도체–금속 (M-S-M) 인터페이스를 역학적으로 조절하는 역할을 한다. 또한, 광원의 추가적인 상호작용은 광전하 생성과 인터페이스 / 접점을 통한 이동을 제어하는 압전-광전자라 불리는 3방향 연결 메커니즘을 생성한다. 압전-광전자 효과를 이용하여, 향상된 광 검출성능의 제공을 위해 세라믹 (KNN), 2원산화물 (ZnO) 그리고 3차 칼코할라이드 (ternary chalcohalides, AVBVICVII)로 구성된 나노 소재의 탐색을 통한 고유 자가발전 광 검출기 개발을 위한 PNG와 PD의 효과적인 일체화 방안을 제시한다.
본 논문의 III 장에서는 조성상 경계 (morphotropic phase boundary, MPB)가 x = 0.5 (K0.5Na0.5NbO3)일 때 나오는, K1-xNxNO3의 화학당량적비를 갖는 고체 상태 반응법 (SSR)에 따른 칼륨 니오브산 나트륨 (KNN)의 합성에 대하여 실험하였다. 압전 합성소재는 알키드 수지바인더에 충전제 / 안료로서 KNN 나노 입자와 함께 제작하였다. KNN의 기계적 에너지 수확 능력은 압전 나노 발전기 (PNG)로 작동하는 캔틸레버빔 진동시스템을 제작하여 조사하였다. 캔틸레버빔에 코팅된 KNN 충전복합체는 7.2g, 14.4g 및 21.6g의 서로 다른 크기의 검증질량 (proof mass, mp)을 이용한 스프링 질량 모델을 사용하였다. 압전 복합체는 질량하중 21.6 g에서 캔틸레버빔에 가해지는 최대 응력하에서 1.4 V의 개방회로 전압 (VOC)이 발생하였다. 이 장에서는 저주파 진동에너지 (<10 Hz)를 수집하기 위한 고감도의 무연 압전 복합 시스템의 개발에 대하여 설명하였다.
다음 단계는 자가발전 광 검출기 (self-powered photodetectors, SPPD)의 개발을 위한 반도체 거동 및 압전 특성의 분석을 실시하였다. IV장에서는 기계적 및 광원에 민감한 다기능 소재에 대하여 연구하였으며, PNG및 PD와 같은 두가지의 다른 에너지 수확 유닛의 제작을 통해 카드뮴 (Cd)을 도판트(Dopant)로 사용한 수열성 1D-ZnO 나노 막대 (ZnO NRs)에 대한 압전 / 반도체 성질의 대칭 튜닝을 개발 및 분석하였다. ZnO NRs의 압전 특성은 VOC=36V, ISC=284μA (순수 ZnO NRs)에서 VOC=15V, ISC=178μA (1 wt% Cd가 첨가된 ZnO NRs)로 압전 출력을 감소시키는 Cd 원자에 의해 크게 영향을 받은 것으로 보인다. 하지만, Cd 1 wt%는 순수한 ZnO NRs (D*=5.4x1010cmH1/2W-1)보다 높은 1x1011cmH1/2W-1의 검출성 한계치 (D*)로 우수한 광 반응 특성을 보였다. 또한 PNG와 PD 간의 외부 병렬 연결을 통한 SPPD 개발을 시도하였다.
5장에서는 도핑 메커니즘을 통해 얻은 비대칭 효과와 PNG와 PD의 내부통합으로 SPPD의 개발을 목표로 하여, 장치의 성능을 제어하는 간단하면서도 효과적인 피에조-포토트로닉 결합에 의한 소자를 제작하였다. 유연 PD는 마이크로와이어 (MW), 산호와 같은 마이크로스트립 (CMS) 및 근모와 같은 마이크로와이어 (F-MW)와 결합한 ZnO 마이크로-구조로 개발되었다. 압축 변형 (- εz = 0.37, 0.75, 1.13, 1.50 및 1.87 %)을 통한 고유 압전 전위의 미세조정은 금속-반도체 (M-S) 인터페이스에서 쇼트키 장벽의 크기(ΦSB1, ΦSB2)를 효과적으로 변화시켰다. 6.72×1010cmH1/2W-1의 검출범위 (D*)와 UV에서 가시영역 (365nm, 405nm 및 535nm)까지 확장된 스펙트럼의 변화에 따른 압전-반도체-광여기와 같은 세가지 매개변수를 동시에 조사 및 분석하였다.
6장에서는 5장에서 도출한 피에조-포토트로닉스에 기반한 PNG와 PD의 내부 통합에 의한 일체형 장치의 개발에 관하여 조사하였다. Zn2+와 함께 뿌려진 강유전성 PVDF 폴리머는 꽃모양의 F-ZnO 나노 막대 (F-ZnO NRs)를 성장시켜 조립된 장치 (F-SPPD)의 유연성을 높이기 위해 프리스탠딩 기재로 사용하였다. F-SPPD는 회전력에 의한 기계적 변형에 충분히 반응하여 5V 및 60nA의 압전 출력을 생성하였다. 또한, 제작한 광 검출기는 인장 변형 조건 (+ε)하에서 75μA (24mW/cm2)의 향상된 UV 광전류 (IPh)특성을 보여주었다.
7장에서는 SbSI와 SbSeI와 같은 새로운 형태의 강유전성-반도체 물질인 3차 칼코할라이드 (AVBVICVII)소재의 다기능 특성을 갖는 SPPD의 개발을 위한 연구를 수행하였다. 또한, 폴리 디메틸실록산 (PDMS), 폴리 비닐리덴 플루오라이드(PVDF) 및 폴리 메틸 메타크릴레이트 (PMMA)와 같이 널리 선호되는 중합체 매트릭스를 갖는 기재를 사용하였다. 광활성 물질은 약 5V / 150nA(SbSI) 및 약 2V / 60nA (SbSeI)의 압전 반응 특성을 보여주었다. 또한, PNG 및 단일 SbSI 마이크로로드 (SMR-PNG)에서의 광활성 반도체의 영향은 하이브리드화한 일체형 자가발전 광 검출기의 개발에 중요 요소인 피에조-포토트로닉 효과를 실현하였다.
본 논문에서는 전원 공급이나 배터리의 추가가 없는 다기능 재료를 이용한 차세대의 유연성있고 착용가능한 광전자 센싱 시스템의 설계를 위한 체계적인 연구를 수행하였다. 또한, 하나의 유닛에 두개의 다른 광 및 압전 특성을 집적화할때 발생하는 외부 연결의 구성요소, 회로장치의 복잡성, 유연성있고 인터페이싱 유닛의 최소화를 위한 중요한 대안을 제시하였다.
Expansion of nanotechnology for the development of nanodevices/sensors is highly demanding to promote next-generation systems in the fields of electronics, communications, optical, medical and defense technologies. With the vast opportunities, it is extremely fascinating for nanosystems to operate self-powered without the requirement of batteries and other external power supplies. In the view of optoelectronics, constructing self-powered photodetectors that works without an external bias voltage/battery/power supply has gained significant attention to cultivate wireless and independent sensing devices. With the perspective, we have developed piezoelectric nanogenerator (PNG) that can serve as self-sufficient power sources for photodetectors (PD). The PNGs utilizes the piezoelectric potentials as a driving force which responds to influential straining of non-centrosymmetric materials. Moreover, the strain induced piezopotential in piezoelectric materials serves to dynamically modulate the metal-semiconductor-metal (M-S-M) interfaces based on piezotronics. Additional interaction of light sources produces a three-way coupling mechanism referred as piezo-phototronics which controls the photo charge generation and transportation across the interfaces/junctions. By using the piezo-phototronic effect, we exhibit the effective internal integration of PNG and PD for the development of intrinsic self-powered photodetectors with exploration of nanomaterials constituting ceramic (KNN), binary oxide (ZnO) and ternary chalcohalides (AVBVICVII) to provide improved photodetection performances.
Chapter III of this thesis covers the synthesis of potassium sodium niobate (KNN) under solid state reaction method (SSR) with stoichiometric ratio of K1−xNxNO3, where the morphotropic phase boundary (MPB) occurs at x = 0.5 (K0.5Na0.5NbO3). A piezoelectric composite system was formulated with KNN nanoparticles as filler/pigment in alkyd resin binder. The mechanical energy harvesting ability of KNN was studied through development of a cantilever beam vibration system acting as piezoelectric nanogenerator (PNG). The KNN filled composite coated on the cantilever beam acted as a spring–mass model that was tested for different proof mass (mp) loadings of 7.2 g, 14.4 g, and 21.6 g. The piezoelectric composite was capable of producing an open-circuit voltage (VOC) of 1.4 V under maximum stress exerted on the cantilever beam, at a mass loading of 21.6 g. Through this chapter, a highly sensitive lead-free piezoelectric composite system for harvesting low-frequency vibration energy (<10 Hz) was explained by accounting to piezoelectric properties.
Next stage involves the analysis of piezoelectric property along with semiconducting behaviour for the development of self-powered sensors in optoelectronics specifically focussed on photodetectors (SPPD). For which, multifunctional materials are explored which are sensitive to mechanical as well as light sources. This motivates to proceed Chapter IV to develop and analyze the symmetric tuning of piezoelectric/semiconducting properties for hydrothermally grown 1D-ZnO nanorods (ZnO NRs) using cadmium (Cd) as the dopant through fabrication of two different energy harvesting units such as piezoelectric nanogenerators (PNG) and photodetectors (PD). The piezoelectric property of ZnO NRs was greatly affected by the Cd atom, which led to a reduction in the piezoelectric output from VOC=36 V, ISC=284 µA (pure ZnO NRs) to VOC=15 V, ISC=178 µA (1 wt% Cd-doped ZnO NRs). However, 1 wt % of Cd showed good photo response with a detectivity (D*) limit of 1x1011cmH1/2W-1, which is higher than that of pure ZnO NRs (D* = 5.4x1010cmH1/2W-1). Further, possible means to demonstrate SPPD was illustrated through external parallel connection between PNG and PD.
With the unsymmetrical effect obtained through doping mechanism and with aim to perform SPPD with internal integration of PNG and PD, simple yet effective route to control the device performance was established through three way coupling piezo-phototronic concept in Chapter V. A flexible PD was developed with ZnO micro-architectures such as micro wire (MW), coral like micro strip (CMS), and fibril like clustered micro wire (F-MW). Fine tuning of intrinsic piezoelectric potentials through compressive strain (- εz = 0.37, 0.75, 1.13, 1.50 and 1.87 %) effectively changed the Schottky barrier heights (SB1, SB2) at metal – semiconductor (M-S) interfaces. The detectivity range (D*) of 6.72× 1010 cmH1/2W-1 and broadened spectral activity extending from UV to Visible region (365 nm, 405 nm and 535 nm) three parameters such as piezoelectric-semiconductor-photoexcitation was concurrently explored and analyzed.
Chapter VI of this thesis steps with an advancement of internal integration of PNG and PD into a single device with detailed piezo-phototronic information acquired through the previous chapters. As an approach, ferroelectric PVDF polymer seeded with Zn2+ was employed as a free-standing substrate to grow floral-like F-ZnO nanorods (F-ZnO NRs) promoting flexibility to the as-fabricated devices (F-SPPD). F-SPPD was able to produce piezoelectric output of ~ 5 V and 60 nA by sufficiently responding to the mechanical deformations under the rotational force. Also, the in-build photodetector showed an enhanced UV photocurrent (IPh) of 75 μA (24 mW/cm2) under the tensile strain condition (+ε).
Through Chapter VII, new type of ferroelectric-semiconductor material, ternary chalcohalides (AVBVICVII) such as SbSI and SbSeI were synthesized and explored as an efficient candidate for SPPD with multifunctional properties. The possibilities of polymeric interface for developing SPPD modules with widely preferred polymer matrices, such as polydimethylsiloxane (PDMS), (Polyvinylidene fluoride) PVDF and polymethyl methacrylate (PMMA) were investigated. The photoactive material generates piezoelectrical responses of ~ 5 V/ 150 nA, SbSI and ~ 2 V/ 60 nA, SbSeI. Further, the influence of photoactive semiconducting properties in PNG and single SbSI micro rod (SMR-PNG) were demonstrated with realization of piezo-phototronic effect aiding to the development of intrinsic self-powered photodetectors. The systematic studies reported in this thesis enables freedom for designing next generation flexible and wearable optoelectronic sensing systems using multifunctional materials that are devoid of additional power supplies or batteries. Moreover, pairing of two different systems in a single unit serves as a scale-down approach to minimize the components of external connection, complexity of the circuitry devices, interfacing units fronting the maturation of flexible optoelectronics.
Author(s)
Yuvasree Purusothaman
Issued Date
2019
Awarded Date
2019. 2
Type
Dissertation
URI
http://dcoll.jejunu.ac.kr/common/orgView/000000008940
Affiliation
제주대학교 대학원
Department
대학원 메카트로닉스공학과
Advisor
김상재
Table Of Contents
Contents i
Nomenclature ix
List of Tables xi
List of Figures xii
Abstract - Korean xxii
Abstract xxvi
CHAPTER-1
Introduction
1.1 Background 1
1.2 Origin and basics of piezo-phototronic effect 2
1.3 Piezo-phototronic devices and applications 4
1.4 Piezo-phototronic effect in optoelectronic applications 5
1.4.1 Piezo-phototronic effect on solar cells 5
1.4.2 Piezo-phototronic effect on LEDs 6
1.4.3 Piezo-phototronic effect on photodetectors 6
1.4.3.1 Schottky contact photodetectors 6
1.4.3.2 p-n junction photodetectors 8
1.5 Self-powered nanosystems for photodetection 9
1.6 Integrated self-powered photodetectors 10
1.7 Objective and scope of thesis 12
1.8 Structure of thesis 15
1.9 References 18
CHAPTER II
Materials, methods and measurement techniques
2.1 Chemical details 21
2.2 Synthesis methodology 24
2.2.1 Solid state reaction (SSR) 24
2.2.2 Hydrothermal method 24
2.2.3 Sonochemical method 25
2.3 Measurement techniques and specifications 26
2.3.1 X-ray diffraction (XRD) 26
2.3.2 Raman spectroscopy 26
2.3.3 UV-Visible Absorption Spectroscopy 27
2.3.4 Fourier Transform Infrared Spectroscopy (FTIR) 27
2.3.5 X-ray Photoelectron Spectroscopy (XPS) 27
2.3.6 Field Emission Scanning Electron Microscope (FESEM) 28
2.3.7 Energy Dispersive X-ray Spectroscopy (EDS) 28
2.3.8 Ferroelectric hysteresis tester (P-E loop) 28
2.3.9 Water contact angle 29
2.4 Device fabrication techniques 29
2.5 Electrical characterizations 30
2.6 Calculation of electrical parameters 31
2.7 References 35
CHAPTER III
Ceramic based Piezoelectric Energy Harvester using K0.5Na0.5NbO3 (KNN) Pigmented Composite
3.1 Introduction 38
3.2 Experimental section 40
3.2.1 Synthesis of nano-sized piezoelectric pigment material (KNN) 40
3.2.2 Formulation of lead-free KNN piezoelectric composite 41
3.2.3 Design of an energy harvester using a lead-free piezoelectric
composite 42
3.2.4 Measurement techniques 43
3.3 Results and Discussion 43
3.3.1 Structural and surface morphological analysis 43
3.3.2 Energy harvesting capability of the piezoelectric composite 51
3.3.2.1 Piezoelectric voltage response without proof mass (mp) 51
3.3.2.2 Piezoelectric voltage response with proof mass (mp) 55
3.3.3 Experimental and theoretical validation of piezoelectric resonance
frequency 57
3.4 Conclusion 63
3.5 References 65

CHAPTER IV
Elucidation of Piezoelectric and Semiconducting Properties of ZnO Nanorods and Cd Doped ZnO Nanorods
4.1 Introduction 70
4.2 Experimental 72
4.2.1 Synthesis of ZnO and Cd-ZnO NRs 72
4.2.2 Growth mechanism of 1D-ZnO NRs 73
4.2.3 Fabrication of randomly oriented Cd-doped ZnO NRs-based
piezoelectric nanogenerator 74
4.2.4 Fabrication of vertically aligned Cd-doped ZnO NRs array-based
UV-sensor (UV-S) 75
4.2.5 Measurement system 77
4.3 Results and discussions 77
4.3.1 Structural and surface morphology analysis of Cd-ZnO NRs 77
4.3.2 Significance of Cd doping in 1D ZnO NRs 84
4.3.2.1 Degradation of piezoelectric response 84
4.3.2.2 Enhancement of UV-photo response 88
4.3.2.3 Mechanism of Cd dopant modulated semiconductor properties of ZnO NRs 98
4.3.3 Realization of a self-powered UV-Sensor (SPUV-S) 100
4.4 Conclusion 102
4.5 References 103
CHAPTER V
Regulation of Charge Carrier Dynamics in ZnO Micro-Architecture Based UV/Visible Photodetector via Photonic-Strain Induced Effects
5.1 Introduction 109
5.2 Experimental section 111
5.2.1 One-step synthesis of vapor phase transport (VPT) technique for
ZnO micro-architectures 111
5.2.2 Fabrication of flexible ZnO microstructures based photodetector 112
5.2.3 Characterization system 113
5.3 Results and discussion 113
5.3.1 Structural and surface morphology of ZnO micro-architectures 113
5.3.2 Photodetection capabilities of ZnO MW, ZnO CMS and ZnO F-MW 119
5.3.3 Piezotronic effect of ZnO F-MW based PD 129
5.3.4 Piezo-phototronic effect of ZnO F-MW PD 134
5.4 Conclusion 137
5.5 References 138
CHAPTER VI
Internally Hybridized Interfacial Quantification to Stimulate Highly Flexile Self-Powered Photodetector
6.1 Introduction 146
6.2 Experimental Section 147
6.2.1 Synthesis of F-ZnO NRs grown in PVDF film 147
6.2.2 Fabrication of flexile self-powered photodetector (F-SPPD) device 148
6.2.3 Instrumentation details 148
6.3 Results and Discussion 149
6.3.1 Structural analysis of in-situ grown F-ZnO NRs/PVDF film 149
6.3.2 I-V characteristics of internally developed F-SPPD 153
6.3.3 Piezotronic modulated optical performance of F-SPPD 156
6.3.4 Conceptualization of self-integrated through piezoelectric
characteristics 159
6.4 Conclusion 163
6.5 References 164

CHAPTER VII
Photoactive Piezoelectric Energy Harvester Driven by Ternary Chalcohalides (AVBVICVII) towards Self-Powered Photodetection
7.1 Introduction 169
7.2 Methods 171
7.2.1. Synthesis of antimony sulfoiodide (SbSI) 171
7.2.2. Synthesis of antimony selenoiodide (SbSeI) 171
7.2.3. Development of SbSI-based piezoelectric nanogenerator (S-PNG) 172
7.2.3.1 SbSI/PDMS composite 172
7.2.3.2 SbSI/PVDF composite 172
7.2.3.3 SbSI/PMMA composite 173
7.2.3.4 SbSeI/PMMA composite 173
7.3 Results and discussion 173
7.3.1. Material analysis 173
7.3.2. Functional dependence of polarization and applied field 178
7.3.3. Evaluation of polymeric interfaces 180
7.3.4. Demonstration of self-powered photodetection 185
7.4 Conclusion 198
7.5 References 200
CHAPTER VIII
Summary and Future Perspective
8.1 Summary 204
8.2 Suggestions for future improvement 207

Appendix A: List of Publications 208
Appendix B: List of Conferences 210
Appendix C: List of Awards 214
Appendix D: Cover Page 215
Appendix E: Patent 216
Degree
Doctor
Publisher
제주대학교 대학원
Citation
Yuvasree Purusothaman. (2019). Development of Intrinsic Self-Powered Photodetectors based on Piezo-Phototronic Effect
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Faculty of Applied Energy System > Mechatronics Engineering
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