Study on the origin and function of high-energy emission around dislocations in III-nitride quantum well structures by nanoscopic spectroscopy

2022 Fiscal Year Final Research Report

• Project/Area Number: 19K04490
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 21050:Electric and electronic materials-related
• Research Institution: Yamaguchi University
• Principal Investigator: Kurai Satoshi 山口大学, 大学院創成科学研究科, 助教 (80304492)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: 窒化インジウムガリウム / 窒化アルミニウムガリウム / 量子井戸構造 / 転位 / ポテンシャル障壁 / 空間分解分光 / カソードルミネッセンスマッピング法 / 近接場光学顕微分光法

Outline of Final Research Achievements

InGaN quantum well (QW) and AlGaN QW structures were characterized using micro-spectroscopy. The origin of the multiple high-energy emission peaks observed in the photoluminescence (PL) spectra of InGaN QWs is attributed to the in-plane inhomogeneity in the quantum well. In addition, a positive correlation between the potential barrier height and the PL emission intensity was found, indicating the usefulness of the potential barrier for the improvement of efficiency. Furthermore, we found the difference in potential barrier height due to different underlying layer structures and pointed out its relation between lattice strain. In AlGaN QWs on off-cut substrates, the relationship between off-cut angle and luminescence efficiency was investigated in detail, and it was shown that the superposition of defect regions and carrier-localized regions decreases the efficiency.

Free Research Field

半導体工学

Academic Significance and Societal Importance of the Research Achievements

本研究では、InGaN QWにおいて貫通転位近傍に自己形成されるポテンシャル障壁の形成機構について考察し、量子井戸面内の不均一性の存在やVピット形成下地層(超格子層、MT-GaN層)の効果が示された。また、ポテンシャル障壁の高さと発光強度、IQEに正の相関が見られ、発光効率改善への有用性も明らかとなった。さらにAlGaN QWにおいて貫通転位が密集した欠陥領域とキャリア局在領域が重畳したことがIQE低下の要因であることを示した。いずれも欠陥領域とキャリア局在領域の制御が発光効率の改善に重要であり、この機構・機能に関するいくつかの知見が得られ、さらなる構造の改善や活用が期待される。