Study on N-polar GaN MIS-HEMTs for power devices

• Project/Area Number: 19H02165
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 21050:Electric and electronic materials-related
• Research Institution: Tohoku University
• Principal Investigator: Suemitsu Tetsuya 東北大学, 未来科学技術共同研究センター, 特任教授 (90447186)
• Co-Investigator(Kenkyū-buntansha): 橋詰 保 北海道大学, 量子集積エレクトロニクス研究センター, 特任教授 (80149898)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Project Status: Completed (Fiscal Year 2022)
• Budget Amount: ¥16,900,000 (Direct Cost: ¥13,000,000、Indirect Cost: ¥3,900,000); Fiscal Year 2021: ¥5,330,000 (Direct Cost: ¥4,100,000、Indirect Cost: ¥1,230,000); Fiscal Year 2020: ¥5,720,000 (Direct Cost: ¥4,400,000、Indirect Cost: ¥1,320,000); Fiscal Year 2019: ¥5,850,000 (Direct Cost: ¥4,500,000、Indirect Cost: ¥1,350,000)
• Keywords: 窒化物半導体 / HEMT / 窒素極性

Outline of Research at the Start

窒素極性GaN結晶を用いた高電子移動度トランジスタ（HEMT）は、ノーマリーオフ動作の実現やナチュラルスーパージャンクション（NSJ）による耐圧向上等の点で、従来から研究開発が行われているGa極性結晶を用いたGaN HEMTに対して優位性があると考える。本研究では、窒素極性HEMTの次世代パワーデバイスへの応用に視点を向け、既存のGa極性HEMTに対する優位性を明らかにする。

Outline of Final Research Achievements

The goal of the research is to demonstrate the advantage of N-polar GaN crystals over Ga-polar GaN counterparts in the field of power devices.
In order to design the device structures, modeling the effect of polarization charges on the band profile of devices is indispensable. To explain the difference of the Schottky barrier height between N-polar and Ga-polar GaN, a new model to assume the polarization surface charges to be distributed in a several-angstrom-width region on surface. The experimentally observed difference in the barrier height is able to be explained if this width of the polarization-charged area is 5 angstroms.

Academic Significance and Societal Importance of the Research Achievements

窒素極性窒化物半導体は作製が難しく、報告例が少ないため、基本的な材料パラメータに関する情報も少ない。ショットキー障壁高さもその一つである。今回提案したモデルにより、GaN以外の材料でも一般的なGa極性結晶での障壁高さが分かっていれば、窒素極性でどれくらいになるのか、その材料の分極電荷密度と誘電率から推測することが可能となり、窒素極性材料を用いたパワーデバイス等のバンドエンジニアリングの際の一助となる。

Research Products

• [Journal Article] Reverse bias annealing effects in N-polar GaN/AlGaN metal-insulator-semiconductor high electron mobility transistors (2021)
  • Author(s): Prasertsuk Kiattiwut、Suemitsu Tetsuya、Matsuoka Takashi
  • Journal Title: Japanese Journal of Applied Physics Volume: 61 Issue: SA Pages: SA1006-SA1006
  • DOI: 10.35848/1347-4065/ac2214
  • Peer Reviewed / Open Access
• [Journal Article] Effective Schottky Barrier Height Model for N‐Polar and Ga‐Polar GaN by Polarization‐Induced Surface Charges with Finite Thickness (2020)
  • Author(s): Suemitsu Tetsuya、Makabe Isao
  • Journal Title: physica status solidi (b) Volume: 257 Issue: 4 Pages: 1900528-1900528
  • DOI: 10.1002/pssb.201900528
  • Peer Reviewed / Open Access
• [Presentation] Impact of polarization-induced charges on Schottky barrier height of polar GaN (2021)
  • Author(s): T. Suemitsu and I. Makabe
  • Organizer: 13th International Symposium on Advanced Plasma Sciene and its Applications for Nitrides and Nanomaterials (ISPlasma)
  • Int'l Joint Research
• [Presentation] Evidence of carrier trapping at extrinsic gate region in N-polar GaN/AlGaN MIS HEMTs (2021)
  • Author(s): K. Prasertsuk, T. Suemitsu and T. Matsuoka
  • Organizer: 13th International Symposium on Advanced Plasma Science and its Applications for Nitrides and Nanomaterials (ISPlasma)
  • Int'l Joint Research
• [Presentation] 分極電荷の広がりを考慮したGa極性・N極性の実効ショットキー障壁高さモデル (2020)
  • Author(s): 末光哲也, 眞壁勇夫
  • Organizer: 第67回応用物理学会春季学術講演会
• [Presentation] Effective Schottky barrier height model for Ga- and N-polar GaN by polarization-induced surface charges with finite depth (2019)
  • Author(s): Suemitsu Tetsuya、Makabe Isao
  • Organizer: International Conference on Nitride Semiconductors
  • Int'l Joint Research