Quantitative analysis of potential barrier in GaInN ternary alloy semiconductor by microscopic spectroscopy and the mechanisms for high quantum efficiency

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K06264
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Electronic materials/Electric materials
• 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): 2016-04-01 – 2019-03-31
• Keywords: 顕微分光 / InGaN / 量子井戸構造 / ポテンシャル障壁 / 貫通転位

Outline of Final Research Achievements

Spatial distribution of local high-energy emissions, which were observed at surface pits originating from threading dislocations in InGaN quantum well (QW) structures fabricated on c-plane sapphire substrates, was evaluated by scanning near-field optical microscopy (SNOM). Low temperature SNOM measurements revealed positional correlation between dark contrast and high-energy emission in blue and green QWs, that is direct observation of self-formation of energy barriers (200 to 300 meV in height) at dislocations. In addition, local high-energy emissions were also observed at threading dislocations in the AlGaN QW structures by cathodoluminescence method. In this case, no surface structure such as surface pits was observed, suggesting the different mechanism from that in the InGaN system.

Free Research Field

半導体工学

Academic Significance and Societal Importance of the Research Achievements

本研究では、下地構造の異なる青色QW、青色に比べ効率の低い緑色QWおよび深紫外AlGaN QWにおいて貫通転位近傍に自己形成される特異なエネルギー障壁の観察および障壁高さの定量評価を行った。貫通転位近傍にエネルギー障壁が形成され、キャリアが欠陥において非発光となるのを抑制することが青色LEDの高効率化に有用とされており、観測された発光エネルギーの空間分布がデバイスの発光効率改善に繋がる可能性を示した。