산화구리막 이종 접합을 적용한 베타갈륨옥사이드 전력소자 공정기술 연구 = Device Performance of β-Ga2O3-based Power Devices Fabricated Using Cu-oxide Hetero-Junctions

다국어 초록 (Multilingual Abstract)

Thermally oxidized CuOₓ thin films have attracted considerable attention as promising anode materials for high-voltage β-Ga2O3 rectifier devices. However, the effects of oxidation temperature on the structural, electronic, and interfacial properties of CuOₓ films, as well as the underlying mechanisms linking these material characteristics to device performance, have not yet been fully elucidated. In particular, the influence of the Cu → Cu2O → CuO phase transition on 캐리어 polarity, band-edge structure, electric-field distribution, and breakdown characteristics remains insufficiently established within a unified material–device framework. In this study, 100-nm-thick Cu films were thermally oxidized in an oxygen ambient over a temperature range of 300–500 °C. The resulting CuOₓ films were systematically characterized in terms of their structural properties (SEM, AFM, and XRD), electronic properties (hall-effect measurements), and optical properties (UV–Vis spectroscopy), and these material characteristics were quantitatively correlated with TCAD-based electrical simulations and the performance of β-Ga2O3 heterojunction diodes. The sample oxidized at 400 °C exhibited a nearly single-phase p-형 Cu2O layer with a smooth surface morphology, a well-defined optical bandgap, and a high hole concentration. As a result, the corresponding β-Ga2O3 heterojunction diode achieved a breakdown voltage of 1155 V, a specific on-resistance of 2.22 mΩ·cm², and a Baliga figure of merit of 0.60 GW·cm⁻². In contrast, devices fabricated at 300 °C suffered from incomplete oxidation, while those processed at 500 °C experienced excessive oxidation into n-형 CuO, leading to interfacial degradation, increased leakage current, and reduced breakdown voltage. These results demonstrate that precise control of the oxidation temperature is a critical factor in achieving a competitive BV–R_on trade-off in β-Ga2O3 heterojunction rectifier devices. Furthermore, this work provides practical guidelines for optimizing Cu2O-based anode processes for next-generation kV-class β-Ga2O3 power electronics.

목차 (Table of Contents)

• 목차 i
• Abstract iii
• 그림 목차 v
• 제 1장. 서론 1
• 1.1 β-Ga2O3 1
• 1.2 이종 접합 파워 디바이스 3
• 1.3 Cu2O 5
• 제 2장. 실험 방법 7
• 2.1 디바이스 프로세스 플로우 8
• 2.2 CuOx 특성 분석 방법 9
• 제 3장. 결과 & 토의 10
• 3.1 CuOx 형성 10
• 3.1.1 색깔 10
• 3.1.2 SEM 11
• 3.1.3 AFM 12
• 3.1.4 XRD 14
• 3.1.5 홀 측정 16
• 3.1.6 UV-Vis 19
• 3.2 T-CAD 시뮬레이션 22
• 3.2.1 Cu2O 밴드 갭에 따른 문턱 전압 변화 23
• 3.2.2 Cu2O 전자 친화도에 따른 전류 밀도 변화 25
• 3.2.3 문헌 값을 적용한 Cu2O I-V 및 항복 전압 특성 26
• 3.2.4 Cu2O 두께에 따른 항복 전압 변화 28
• 3.2.5 Cu2O 도핑 농도에 따른 항복 전압 변화 30
• 3.2.6 Cu2O 도핑 농도에 따른 공핍 폭 변화 32
• 3.3 디바이스 특성 35
• 3.3.1 순방향 전기적 특성 36
• 3.3.2 역방향 전기적 특성 39
• 3.4 Baliga 성능 지수 41
• 3.5 문헌 벤치 마킹 43
• 제 4장. 결론 45
• 제 5장. 참고 문헌 46