Enhanced Quantum Dot Solar Cell through Structural Analysis and Post-process
- 주제(키워드) Quantum Dot Solar Cell , High Temperature Growth , InGaAs-capped InAs Quantum Dot , Hydrogen Plasma Treatment
- 발행기관 고려대학교 대학원
- 지도교수 박정호
- 발행년도 2013
- 학위수여년월 2013. 8
- 학위구분 박사
- 학과 일반대학원 전자전기공학과
- 원문페이지 108 p
- 실제URI http://www.dcollection.net/handler/korea/000000046417
- 본문언어 영어
- 제출원본 000045764483
초록/요약
InGaAs-capped InAs quantum dots (QDs) and InAs QDs were adopted for the study of the effects through growth temperature and the band structure of InAs QDs on the performance of GaAs-based QD solar cell. It has been shown that the defects due to low temperature growth resulted in the decrease of VOC, JSC and external quantum efficiency for GaAs bulk solar cell and QD embedded solar cells. It has been also found that InAs QDs act as defects by trapping photo-generated carries which affect the carrier transport in QD solar cell. The QD solar cell with InGaAs-capped InAs QDs showed higher performance than the QD solar cell with only InAs QDs. Such result has been explained by photo-generated carrier trapping and tunneling through InGaAs QW state in InGaAs-capped InAs QDs. Hydrogen plasma treatment one of post-process is adopted to reduce such defects. It is observed that JSC and EQE of range related QDs are increased due to reduction of defects near QDs. It is revealed that hydrogen plasma treatment enhances property of QDs, thus photovoltaic efficiency is increased. QD solar cells are showed higher efficiency under concentration light, therefore QD solar cells with high temperature growth, H plasma treatment and concentrated light system have potential in the future.
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CONTENTS
ABSTRACT i
Enhanced Quantum Dot Solar Cell through Structural Analysis and Post-process i
LIST OF FIGURES vi
LIST OF TABLES ix
1. Introduction １
1.1. InAs/GaAs Quantum Dot Solar Cells １
1.2. Growth of InAs QD on GaAs ７
1.3. Organization of Dissertation ８
2. Theoretical Background １０
2.1. QD layers in built-in electric field １０
2.2. Carrier path between QDs １１
2.3. Increased short-circuit current density of QD solar cell １２
2.4. Carrier confinement and flow in QD and DW structure １８
2.5. Analysis of tunneling probability in QDs ２０
2.6. N-doped QDs to prevent carrier-trapping ２７
3. Device Fabrication ２８
4. Characteristics of Quantum Dot Solar Cell ３１
4.1. Direct-doped quantum dot solar cell ３１
4.1.1. Structures of bulk solar cell and quantum dot solar cell ３１
4.1.1. I-V characteristics and photovoltaic efficiency of bulk SC and QDSC ３３
4.1.2. External quantum efficiency of bulk SC and QDSC ３６
4.2. QD solar cell with high temperature growth method ３７
4.2.1. Structures of solar cell with high temperature growth ３７
4.2.2. EQE of LT and HT bulk SC ３９
4.3. InGaAs-capped InAs QD solar cell ４０
4.3.1. Structures of InAs QDSC and InGaAs-capped InAs QDSC ４０
4.3.2. Optical characteristic of HT QDSC and HT DWSC ４２
4.3.3. I-V characteristic (JSC, VOC, dark current) of LT and HT bulk SC and QDSC ４４
4.3.4. EQE and analysis of quantized state ４９
5. Hydrogen Plasma Treatment by PECVD ５２
5.1. Hydrogen plasma treatment system ５２
5.2. Characteristics of H plasma ５４
5.2.1. H plasma penetrating depth on GaAs ５４
5.2.2. H plasma effect on ohmic contact ６０
5.3. Enhanced InAs QD by H plasma treatment ６３
5.3.1. Characteristic of InAs QD with process time ６３
5.3.2. Characteristic of InAs QD with RF power ６６
5.4. Property of QD solar cell with HPT ６９
5.4.1. I-V characteristics with HPT ６９
5.4.2. EQE with HPT ７１
6. Advanced Quantum Dot Solar Cell ７２
6.1. QD solar cell with HPT ７２
6.2. Photovoltaic measurement on concentrated light ７５
7. Conclusion ７６
REFERENCES ７９
국문 요약 ８４
Curriculum Vitae ８７
감사의 글 ９２
