Reduction in current collapse and enhancement of breakdown voltage in GaN-based HEMTs

2019 Fiscal Year Final Research Report

• Project/Area Number: 16K06314
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Electron device/Electronic equipment
• Research Institution: Shibaura Institute of Technology
• Principal Investigator: Horio Kazushige 芝浦工業大学, システム理工学部, 教授 (10165590)
• Project Period (FY): 2016-04-01 – 2020-03-31
• Keywords: 窒化ガリウム / HEMT / 電流コラプス / 耐圧 / フィールドプレート / バッファ層 / ２次元解析

Outline of Final Research Achievements

So-called current collapse and breakdown voltage in field-plate AlGaN/GaN HEMTs with a deep acceptor in the semi-insulating GaN buffer layer are studied.
It is shown that when the acceptor density is higher, the current collapse is reduced due to the field-plate effect and the breakdown voltage is enhanced. It is also analyzed how the breakdown voltage of AlGaN/GaN HEMTs with a high-k passivation layer depends on the gate-to-drain distance. As a result, the breakdown voltage increases as the gate-to-drain distance increases, indicating that the electric field between gate and drain are almost uniform (～ 3 MV/cm).In addition, a double passivation structure with a thin SiN layer and a relatively thick high-k passivation layer is analyzed, showing that the breakdown voltage is enhanced due to the high-k layer effect.

Free Research Field

半導体電子工学

Academic Significance and Societal Importance of the Research Achievements

AlGaN/GaN HEMTは高電力マイクロ波デバイス及び高電力スイッチングデバイスとして注目されている。しかしながら，GaNデバイスに通常見られる電流コラプスはマイクロ波電力の低下やオン抵抗の増大につながり，また実験的に得られる耐圧は理論的なものよりかなり低い。そこで，AlGaN/GaN HEMTの電流コラプスを低減したり，その耐圧を向上することは非常に意味のあることである。本研究で得られた，電流コラプスを低減する方法や耐圧を向上する方法はこれらを改善するものとして価値の高いものと思われる。