2007 Fiscal Year Final Research Report Summary
Nano-analysis of occupation sites of impurity atoms and relation with functional characteristics
| Project/Area Number |
17360012
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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 | 一般 |
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| Research Field |
Applied materials science/Crystal engineering
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| Research Institution | Kyushu University |
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Principal Investigator |
KUWANO Noriyuki Kyushu University, Art, Science and Technology Center for Cooperative Research, Professor (50038022)
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| Co-Investigator(Kenkyū-buntansha) |
KANGAWA Yoshihiro KYUSHU UNIVERSITY, Research Institute for Applied Mechanics, Associate Professor (90327320)
HATA Satoshi KYUSHU UNIVERSITY, Interdisciplinary Graduate School of Engineering Sciences, Associate Professor (60264107)
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| Project Period (FY) |
2005 – 2007
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| Keywords | Indium nitridp / Molecular beam enitaxv / Transmission electron microscopy / Oxygen atom / Energy gap / ALCHEMI / Crystal polarity / Interstitial atom site |
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| Research Abstract |
First of all, the method to prepare a high quality thin foil specimens for transmission electron microscope (TEM) observations was developed: It was confirmed that prior to focused ion beam (FIB) milling, a mesh-disk should be dimpled in order to make possible a final polishing with an Argon ion mill to remove damaged surface layers. The specimens for the present analyses were InN thin films grown by molecular beam epitaxy method (MBE) on a (0001) sapphire substrate. The content of oxygen in this InN thin films was analyzed separately to be 3% or less, and its energy gap was estimated by an optical absorption method to be approximately 1.2 eV. TEM analysis revealed that the InN thin film is composed of an aggregate of [0001] columnar crystals about 50 - 100 nm in diameter. The growth direction was [0001], but a-axis was oriented randomly on the growth plane. Convergent electron beam diffraction (CBED) analysis confirmed that the growth direction is N-polarity.
InN crystallizes in a wurtzite structure that has two positions for interstitials; T(x,y,z)=(0, 0, "5/8) and O(x,y,z)=(2/3, 1/3, "z).From the atom location enhanced microanalyses (ALCHEMI)with (0001) plane channeling, and (1-100) plane channeling revealed that impurity oxygen atoms occupy the nitrogen atoms sites instead of the interstitial sites. Under an assumption that such substitution generates one electron carrier per one oxygen atom, 3%oxygen is expected to raise the effective energy-gap by several tenth eV with an approximation of nearly free electron model. This result strongly suggests that the change in energy-gap is explained by Moss-Burstain model.
The results of the present research are quite important information that is useful to investigation of defect structures of InN, the diffusion process of oxygen atoms.
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[Journal Article] InN polarity determination by convergent-beam electron diffraction2005
Author(s)
T., Mitate, S., Mizuno, H., Takabara, R., Kakegawa, T., Matsuoka, N., Kuwano
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Journal Title
Appl. Phys. Lett 66
Pages: 134103.1-134103.3
Description
「研究成果報告書概要(欧文)」より
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[Presentation] TEM specimen preparation with FIB-μ-sampling unit for opto-functional materials2007
Author(s)
Y., Kugiyama, T., Yokote, S., Momii, M., Hijikuro, Y., Nakahara, N., Kuwano, T., Sekiguchi
Organizer
63rd Meeting of Japanese Society of Micrscopy
Place of Presentation
Toki-Messe(Niigata)
Year and Date
20070520-22
Description
「研究成果報告書概要(欧文)」より
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[Presentation] Location of impurity oxygen atoms in InN grown by MBE2007
Author(s)
S., Momii, D., Koba, N., Kuwano, S., Hata, M., Yoshimoto
Organizer
3rd Asia-Pacific Workshop on Wide-gap Semiconductors(APWS-2007)
Place of Presentation
Jeonju, Korea
Year and Date
20070311-14
Description
「研究成果報告書概要(欧文)」より
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