2001 Fiscal Year Final Research Report Summary
Metal contact formation to GaN based on the interface control technologies
| Project/Area Number |
11555081
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
Electronic materials/Electric materials
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| Research Institution | HOKKAIDO UNIVERSITY |
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Principal Investigator |
HASHIZUME Tamotsu Hokkaido Univ., Res. Center for Integrated Quantum Electronics, Ass. Pro., 量子集積エレクトロニクス研究センター, 助教授 (80149898)
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| Co-Investigator(Kenkyū-buntansha) |
KASAI Seiya Hokkaido Univ., Grad. School of Eng., Ass. Pro., 大学院・工学研究科, 助教授 (30312383)
KANESHIRO Chinami Kanagawa Inst. Technol., Faculty of Eng., Inst., 工学部, 助手 (30318993)
MOTOHISA Junichi Hokkaido Univ., Res. Center for Integrated Quantum Electronics, Ass. Pro., 量子集積エレクトロニクス研究センター, 助教授 (60212263)
SEKI Shouhei Oki Electric Co. Ltd., Senior Res., 半導体技術研究所, グループリーダー(研究職)
TAKEYAMA Mayumi Kitami Inst. Technol., Ass. Pro., 工学部, 助教授 (80236512)
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| Project Period (FY) |
1999 – 2001
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| Keywords | Gallium Nitride / surface control / interface control / Schottky contact / ohmic contact / Fermi level pinnning / surface treatment / natural oxide |
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| Research Abstract |
The purpose of this research was to develop the formation processes of a stable Schottky contact and a ohmic contact with a low resistivity to GaN, based on the systematic characterization of the GaN surfaces and metal-GaN interfaces. The main results obtained are listed below:
(1) Chemistry and electronic properties of GaN surfaces after various kinds of surface treatments were characterized by x-ray photoelectron spectroscopy (XPS). Strong upward band bending of 1.4 eV was found at the air-exposed GaN surface. This is due to the high density of surface state. The surface treatment in the NH_4OH solution and the ECR-excited N_2 plasma significantly decreased the surface band bending to 0.5 eV, indicating the reduction of the Fermi level pinning.
(2) We investigated the leakage mechanism through metal/n-GaN interfaces by detailed current-voltage-temperature (I-V-T) measurements. A large deviation from the thermionic emission (TE) transport was observed in the reverse I-V curves with a la
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rge excess leakage. A novel barrier- modified thermionic-field emission (TFE) model based on presence of near-surface fixed changes or surface states was proposed to explain the observed large reverse leakage currents.
(3) A novel surface passivation process for AlGaN/GaN heterostructures utilizing an ultrathin Al_2O_3 layer (〜 1 nm) was proposed. The reverse leakage current for the Schottky gate contact on the Al_2O_3-passivated heterostructure surface was reduced by three orders of magnitude than that for the conventional Schottky gate structure. C-V results showed good gate controllability two-dimensional electron gas (2DEG) by the novel gate structure.
(4) Mg-doped GaN surfaces were characterized by XPS. The surface accumulation of Mg at the Mg-doped GaN seems to cause the formation of the disordered surface layer including a tenacionus oxide layer, leading to the large downward band-bending of 1.3-1.4 eV at the surface. The surface treatment in ECR-N_2 plasma was very effective in removing such a disordered layer. Less
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Research Products
(28 results)
