Study on Ultraviolet-Emitting Devices based on Bi3+-doped Orthophosphate Films
- Alternative Title
- Bi3+ 가 도핑된 오르토인산염 필름 기 자외선 발광 소자에 관한 연구
- Abstract
- 자외선, 특히 자외선-C 스펙트럼은 표피에 침투하여 피부 손상을 초래하기 때 문에 유해 물질로 분류되는 경우가 많다. 그럼에도 불구하고 적절한 세기로 조사하 면 자외선-C는 학술 및 산업 응용 분야 모든 곳에서 활용이 가능하다. 따라서 환경 친화적인 자외선-C의 발전은 최근 상당한 관심을 받고 있다. 본 연구에서는 실리콘 기판에 Bi3+가 도핑된 LnPO4 (Ln = Y 및 Lu) 박막을 사용하여 자외선-C를 방출 하는 발광소자를 소개한다. 이러한 필름은 간단하고 경제적으로 실행 가능한 졸겔 스핀 코팅 기술을 사용하여 합성되며, 외부 불순물이 없으며 잘 결정화된 제노타임 의 정방정계 오르토인산염 구조를 형성한다. Bi3+가 도핑된 LnPO4 박막을 실리콘 기판에 증착하여 교류 정현파으로 작동하는 최초의 전계 발광 자외선-C 소자를 성 공적으로 구현하였다. 다음으로는 수성 염화나트륨 전해질 내에서 동일한 박막을 활 용한 발광 소자를 전해질-전계발광 방식으로 도입하였다. 모든 장치는 약 240nm의 중심이 되는 피크 파장을 가진 자외선-C 방출을 하며, 이는 광학적으로 정방정계 오 르토인산염 격자 내에서 Bi3+ 이온의 전자 전이에 기인한다. 또한 장치의 형태학적, 전기적, 광학적 특성에 대한 분석을 진행했다. 따라서 이 연구는 비용 면에서 효율 적이고 환경적으로 지속 가능한 자외선-C 발광 소자를 실현하여 기존의 수은 기반 자외선 램프를 대체할 수 있는 방법론을 제공한다. 키워드: 자외선-C, 오르토인산염, Bi3+, YPO4, LuPO4|Ultraviolet (UV) radiation, particularly the UVC spectrum, is frequently classified as a harmful substance due to its capacity to penetrate the skin epidermis, resulting in dermal damage. Nonetheless, when administered in appropriate dosages, UVC radiation can serve beneficial purposes in both academic and industrial applications. Consequently, the research on alternative environmentally friendly UVC sources has garnered significant interest in recent times. In this dissertation, a series of UVC-emitting devices are introduced, employing Bi3+-doped LnPO4 (Ln = Y and Lu) thin films deposited on a silicon substrate. These films are synthesized using a straightforward and economically viable sol-gel spin coating technique, resulting in well-crystallized orthophosphate structures of the xenotime tetragonal variety, devoid of any residual or unwanted impurities. Through the integration of a thin Au transparent electrode, the first UVC device is successfully realized, functioning under an alternating current sinusoidal waveform in the capacity of an electroluminescent (EL) device. Following this, utilizing the same thin film in an aqueous sodium chloride electrolyte, the second device is introduced as an electrolyte-assisted EL device. All devices display UVC emission with a peak wavelength centered at ~240 nm, which is optically ascribed to the electronic transitions of Bi3+ ions within the tetragonal orthophosphate lattice. Moreover, thorough analyses of the morphological, electrical, and optical characteristics of the devices are conducted. Hence, this investigation may offer a viable methodology for the realization of cost-effective and environmentally sustainable UVC-emitting devices, serving as replacements for traditional mercury-based UV lamps. Keywords: ultraviolet-C, orthophosphate, Bi3+, YPO4, LuPO4
- Issued Date
- 2025
- Awarded Date
- 2025-02
- Type
- Dissertation
- Publisher
- 국립부경대학교 대학원
- Affiliation
- 국립부경대학교 대학원
- Department
- 대학원 융합디스플레이공학과
- Advisor
- Jongsu Kim
- Table Of Contents
- Chapter 1. Introduction 1
1.1 Introduction 1
1.2 References 4
Chapter 2. Background and Theoretical Basis 6
2.1 Ultraviolet (UV) 6
2.1.1 UV spectroscopy 6
2.1.2 UV applications 7
2.2 Phosphor 9
2.2.1 Definition of phosphor 9
2.2.2 Luminescence mechanism in phosphor 11
2.3 Orthophosphates 14
2.4 Bismuth activator 16
2.5 Inorganic electroluminescence 18
2.5.1 AC-driven electroluminescence (ACEL) mechanism 19
2.5.2 Electrolyte-assisted semiconductor 22
2.6 References 23
Chapter 3. Experimental Method 26
3.1 Materials 26
3.2 Synthesis of Bi3+-doped LnPO4 films (Ln = Y and Lu) 26
3.2.1 P2O5 26
3.2.2 Y-O:Bi3+ 27
3.2.3 Lu-O:Bi3+ 27
3.2.4 LnPO4:Bi3+ thin films fabrication 28
3.3 Aqueous NaCl electrolyte 30
3.4 Ultraviolet-emitting electroluminescence 30
3.5 Electrolyte-assisted electroluminescence 31
3.6 Measurements and instruments 33
3.6.1 Crystal phase 33
3.6.2 Cross-section morphology 34
3.6.3 Surface chemical state and surface topography 34
3.6.4 Electronic state morphology 34
3.6.5 Optical properties measurement 35
3.6.6 Electro-optical transient behavior 35
3.7 References 36
Chapter 4. Crystallography, Morphology, and Carrier Properties of the Bi3+-doped LnPO4 films 37
4.1 Crystal phase morphology 37
4.1.1 YPO4:Bi3+ 37
4.1.2 LuPO4:Bi3+ 45
4.2 Surface chemical state interpretation 50
4.3 Cross-sectional and surface topography 57
4.4 Semiconductor properties 61
4.5 References 64
Chapter 5. UVC-Emitting Devices based on Orthophosphate Films 68
5.1 Design interpretation 68
5.1.1 Flat-band energy diagram 68
5.1.2 Aqueous NaCl-assisted electroluminescence 71
5.2 Optical characteristics 74
5.2.1 UV-Vis photoluminescence and photoluminescence excitation 74
5.3 Electroluminescence 80
5.3.1 EL spectral characteristics 80
5.3.2 Voltage and frequency dependency 83
5.3.3 Transient behavior 89
5.3.4 EL performance compared to film-based UV-EL devices 92
5.4 Electrolyte-assisted electroluminescence 97
5.4.1 EEL spectral characteristics 97
5.4.2 Voltage and frequency dependency 98
5.4.3 EEL transient behavior 102
5.4.4 Reliability 104
5.7 References 108
Chapter 6. Conclusion and Future Works 112
6.1 Chapter overview 112
6.2 Conclusion on the synthesis of LnPO4:Bi3+ 113
6.3 Conclusion on the UVC EL device based on LnPO4:Bi3+ 114
6.4 Conclusion on the UVC electrolyte-assisted EL device 115
6.6 Future works 116
6.6.1 Incorporation of trivalent RE activator and structural optimization 116
6.6.2 UVC-emitting device based on Xe excimer lamp 118
6.7 References 119
- Degree
- Doctor
- Appears in Collections:
- 대학원 > 융합디스플레이공학과
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