Development of InN semiconductors for application of thermoelectric conversion devices

2018 Fiscal Year Final Research Report

• Project/Area Number: 16H03860
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Crystal engineering
• Research Institution: Ritsumeikan University
• Principal Investigator: Araki Tsutomu 立命館大学, 理工学部, 教授 (20312126)
• Co-Investigator(Kenkyū-buntansha): 名西 やす之 立命館大学, 理工学部, 授業担当講師 (40268157)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 窒化インジウム / 分子線エピタキシー / 結晶成長 / 転位 / プラズマ / 熱電変換 / 透過電子顕微鏡

Outline of Final Research Achievements

The objective of this research is to reduce threading dislocation density in InN to clarify its applicability for thermoelectric conversion device.
We propose a new approach which provides a simple but effective growth process for threading dislocation reduction in InN film with in situ surface modification by RF-MBE. In this method, we apply nitrogen radical irradiation to modify surface morphology of InN template in situ in MBE growth chamber before regrowing InN film on the template. Transmission electron microscopy (TEM) revealed that threading dislocation density in InN grown with this method reduced by a factor of 3. We clarified that the mechanism of the threading dislocations reduction was due to the inclination, fusion, and annihilation of edge dislocations at the regrowth interface. In addition, the repeatability of this method was also investigated. TEM showed evidence that the threading dislocation density was successfully reduced step by step.

Free Research Field

半導体結晶工学

Academic Significance and Societal Importance of the Research Achievements

本研究では、InN薄膜中の結晶欠陥（貫通転位）を低減するための新しい手法を提案するとともに、その転位低減メカニズムの解明を果たした。従来の転位低減手法は、マスクプロセスやエッチングの前処理が必要でありプロセスが煩雑であったが、本研究で提案する窒素ラジカル照射によるInN表面改質は、in situでInN成長中に行うことができ、成長プロセスの簡便化が可能とした。デバイスの実用化にはさらなる転位密度の低減が求められるが、新しい手法による貫通転位密度低減効果を実証した意義は大きい。また転位密度低減が実現されているメカニズムを明らかにし、さらなる転位密度低減に有効な転位の挙動を導くための指針を示した。