Scallop 구조 수직 나노선 포토다이오드 어레이의 크로스토크 특성 분석 = Crosstalk Characteristics in Scallop-Structured Vertical Nanowire Photodiode Arrays

다국어 초록 (Multilingual Abstract)

High-performance near-infrared (NIR) photodetectors are essential components in a wide range of applications, including medical imaging, biomedical diagnostics, autonomous vehicle sensing, optical communication, and general-purpose photonic systems. As pixel dimensions continue to shrink, electrical crosstalk between neighboring pixels becomes increasingly problematic, leading to degradation in sensitivity and overall image fidelity. To address this challenge, photodiode architectures must be optimized to enhance optical response while suppressing unwanted lateral carrier diffusion.
In this study, scallop-shaped silicon nanowire photodiodes are investigated as a geometry that provides substantially enhanced optical absorption compared with conventional planar and vertical nanowire photodiode structures. Furthermore, the effects of substrate thickness, guard-ring doping conditions, and deep trench isolation (DTI) depth on lateral carrier diffusion and associated electrical crosstalk are systematically analyzed using TCAD simulations. Prior to the analysis, the simulation framework is validated against previously reported electrical characteristics of planar silicon photodiodes to ensure the reliability of the model. The results reveal that, for thin substrates (10–25 µm), deeply formed and highly doped guard-rings with the same doping type as the substrate can significantly suppress lateral electron transport while preserving external quantum efficiency. In contrast, for thicker substrates (150–300 µm), guard-rings with the opposite doping type to the substrate provide improved crosstalk suppression by enabling electrical collection of carriers spreading laterally. DTI structures with comparable depths are effective only in thin substrates, as their ability to suppress crosstalk in thick substrates is limited by incomplete blocking of deeply diffused carriers.
These findings provide quantitative design criteria for selecting appropriate substrate thicknesses and isolation structures in NIR photodiodes. Furthermore, the results offer practical guidance for the development of high-resolution image sensors with improved sensitivity and reduced electrical crosstalk.

목차 (Table of Contents)

• 1. 서 론 1
• 2. 이론적 배경 4
• 2.1. 포토다이오드 구조 4
• 2.1.1. 평판형 포토다이오드 5
• 2.1.2. 수직 나노선 포토다이오드 5
• 2.1.3. 스캘럽 수직 나노선 포토다이오드 6
• 2.2. 크로스토크(Crosstalk) 7
• 2.2.1. 전기적 크로스토크 8
• 2.2.2. 광 흡수 깊이와 전기적 크로스토크 관계 9
• 2.2.3. 크로스토크 차단 기술 9
• 2.3. 연구 동기 및 목적 10
• 3. 전산모사 방법 12
• 3.1. 광학적 시뮬레이션 방법 13
• 3.2. 전기적 시뮬레이션 방법 15
• 4. 전산모사 결과 및 분석 17
• 4.1. 구조별 광 검출 성능 비교 17
• 4.1.1. 실측 데이터 기반 전산모사 모델 보정 17
• 4.1.2. 광 검출 성능 비교 19
• 4.2. 기판 두께에 따른 전기적 크로스토크 차단 성능 분석 25
• 4.2.1. Guard-Ring 설계 변수 변화에 따른 특성 분석 27
• 4.2.2. DTI 설계 변수 변화에 따른 특성 분석 42
• 4.2.3. Guard-Ring 및 DTI의 크로스토크 차단 성능 비교 47
• 5. 결 론 51
• 참 고 문 헌 53