Curriculum Vitaes
Profile Information
- Affiliation
- Professor, Faculty of Science and Technology, Department of Engineering and Applied Sciences, Sophia University(Concurrent)Director of the Institute of Semiconductor Research
- Degree
- 工学士(上智大学)工学修士(上智大学)博士(工学)(上智大学)
- Researcher number
- 90266073
- J-GLOBAL ID
- 200901002456943226
- researchmap Member ID
- 1000167938
Reserach Field: Semiconductor Engineering, Optical and Quantum Electronics,
Nano-crystal Engineering, Organic Semiconductor Devices
Classes: Analog Electronics Circuit, Optoelectronics, Engineering of Optoelectronic Devices, Engineering and Applied Sciences Lab.1, Engineering and Applied Sciences Lab. 2, Information fluency (Build a WEB page using HTML and css)
(Subject of research)
Development of III-nitride nano-columnar crystals for device application
Research on multi-color emission mechanism of InGaN nanocolumns and their application for light emitting device
Short Wavelength semiconductor laser
Research Interests
14Research Areas
3Research History
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Apr, 1992 - Mar, 1994
Education
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Apr, 1983 - Mar, 1987
Awards
2Papers
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Extended Abstract of the 2023 International Conference on Solid State Devices and Materials, Sep, 2023 Peer-reviewedLast authorCorresponding author
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Extended Abstract of the 2022 International Conference on Solid State Devices and Materials, Sep, 2022 Peer-reviewedLast authorCorresponding author
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Japanese Journal of Applied Physics, 61(SC) SC1078-SC1078, Mar 25, 2022 Peer-reviewedLast authorCorresponding authorAbstract The fabrication technology for photonic crystals (PhCs) pertaining to the near-infrared region is mature, and the development of highly functional PhCs using low-symmetry nanoholes is rapidly progressing. In the visible region, InGaN/GaN systems that have good luminescent and electrical properties are the most promising candidate materials for such types of highly functional PhCs, but the development is not progressing. In this study, we report on the basic design parameters and a new fabrication method for InGaN/GaN-based PhC membranes by combining hydrogen environment anisotropic thermal etching based on hydrogen-assisted thermal decomposition and nitric acid wet etching of the AlInN sacrificial layer. Using this method, we fabricated high-quality InGaN/GaN multiple-quantum-well PhC membrane structures having six-membered rings of well-formed fine equilateral triangular nanoholes with a side length of 100 nm. Enhanced green room-temperature photoluminescence with an intensity nine times higher than that of as-grown wafers was observed for the PhC membrane.
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Journal of Crystal Growth, 575 126338-126338, Dec, 2021 Peer-reviewedLast author
Misc.
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applied physics, 84(1) 66-70, Jan 10, 2015
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Meeting abstracts of the Physical Society of Japan, 68(1) 790-790, Mar 26, 2013
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Meeting abstracts of the Physical Society of Japan, 68(1) 848-848, Mar 26, 2013
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Meeting abstracts of the Physical Society of Japan, 68(1) 194-194, Mar 26, 2013
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Technical report of IEICE. OME, 112(57) 25-29, May 17, 2012Thin film deposition characteristics of a Nano-Mist Deposition (NMD) technique: a kind of electrospray deposition technique, using green emission polymer of F8BT. The deposition area was enlarged to 47mm in diameter by increasing a distance between nozzle and substrate. By controlling some deposition conditions, the surface roughness (Ra) of the F8BT layer was reduced to 4.9nm. The NMD was applied to form the F8BT layer of AZO/F8BT/MoO_3 inorganic-organic hybrid LED. The obtained device characteristics were comparable to that of reference device whose active layer was formed by spin-coating method. Furthermore, we demonstrated a fabrication of multiple-stacked organic layer (TPD/F8BT/BCP: low-molecular/ high-molecular/low-molecular) OLED by NMD and obtained a clear rectification characteristics and current injection emission.
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Meeting abstracts of the Physical Society of Japan, 67(1) 748-748, Mar 5, 2012
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IEICE technical report. Electron devices, 111(290) 127-130, Nov 17, 2011We demonstrated the longest wavelength operation of InGaN-based LEDs emitting at 1.46 μm under DC current injection at the room temperature; the LED consists of the p-type Ga-rich InGaN cladding layer, In-rich InGaN active layer, and regularly arranged n-type GaN nanocolumns. In composition of cladding and active layer are estimated to be 〜31% and 〜87%, respectively, from luminescence peak position, STEM-EDX, and SAED analysis. This is the first demonstration of infrared LED based on III-V nitrides and an initial step toward InGaN-based infrared optical devices.
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Proceedings of the Society Conference of IEICE, 2011(1) 247-247, Aug 30, 2011
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Meeting abstracts of the Physical Society of Japan, 66(2) 182-182, Aug 24, 2011
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Meeting abstracts of the Physical Society of Japan, 66(2) 734-734, Aug 24, 2011
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Meeting abstracts of the Physical Society of Japan, 66(2) 734-734, Aug 24, 2011
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Meeting abstracts of the Physical Society of Japan, 66(2) 671-671, Aug 24, 2011
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Meeting abstracts of the Physical Society of Japan, 66(2) 789-789, Aug 24, 2011
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Meeting abstracts of the Physical Society of Japan, 66(1) 753-753, Mar 3, 2011
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Meeting abstracts of the Physical Society of Japan, 66(1) 735-735, Mar 3, 2011
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Meeting abstracts of the Physical Society of Japan, 66(1) 752-752, Mar 3, 2011
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Meeting abstracts of the Physical Society of Japan, 66(1) 712-712, Mar 3, 2011
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Proceedings of the IEICE General Conference, 2011(1) 262-262, Feb 28, 2011
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Meeting abstracts of the Physical Society of Japan, 65(2) 139-139, Aug 18, 2010
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Meeting abstracts of the Physical Society of Japan, 65(2) 139-139, Aug 18, 2010
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Meeting abstracts of the Physical Society of Japan, 65(2) 711-711, Aug 18, 2010
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Meeting abstracts of the Physical Society of Japan, 65(2) 712-712, Aug 18, 2010
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Meeting abstracts of the Physical Society of Japan, 65(2) 735-735, Aug 18, 2010
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Meeting abstracts of the Physical Society of Japan, 65(1) 789-789, Mar 1, 2010
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IEICE technical report, 109(288) 13-16, Nov 12, 2009We demonstrated selective-area growth of InN on Sapphire (0001) substrates by use of molybdenum-mask selective area growth (SAG) of rf-plasma-assisted molecular beam epitaxy (RF-MBE). The well-aligned selective-area grown InN crystals, which have a diameter of 1.0μm, a height of 1.5μm, and a pitch of 1.0μm, showed high crystalline-quality with the room-temperature (RT) photoluminescence (PL) FWHM of 54meV and the PL peak energy of 0.63eV. This suggests that we have grown high-quality InN crystals directly on sapphire substrates without using GaN templates or any buffer layers and also catalyst.
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IEICE technical report, 109(289) 13-16, Nov 12, 2009We demonstrated selective-area growth of InN on Sapphire (0001) substrates by use of molybdenum-mask selective area growth (SAG) of rf-plasma-assisted molecular beam epitaxy (RF-MBE). The well-aligned selective-area grown InN crystals, which have a diameter of 1.0μm, a height of 1.5μm, and a pitch of 1.0μm, showed high crystalline-quality with the room-temperature (RT) photoluminescence (PL) FWHM of 54meV and the PL peak energy of 0.63eV. This suggests that we have grown high-quality InN crystals directly on sapphire substrates without using GaN templates or any buffer layers and also catalyst.
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Meeting abstracts of the Physical Society of Japan, 64(2) 662-662, Aug 18, 2009
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Meeting abstracts of the Physical Society of Japan, 64(2) 666-666, Aug 18, 2009
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Meeting abstracts of the Physical Society of Japan, 64(2) 639-639, Aug 18, 2009
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Meeting abstracts of the Physical Society of Japan, 64(1) 750-750, Mar 3, 2009
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Meeting abstracts of the Physical Society of Japan, 64(1) 158-158, Mar 3, 2009
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Meeting abstracts of the Physical Society of Japan, 64(1) 158-158, Mar 3, 2009
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Meeting abstracts of the Physical Society of Japan, 64(1) 727-727, Mar 3, 2009
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Meeting abstracts of the Physical Society of Japan, 64(1) 728-728, Mar 3, 2009
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IEICE technical report, 108(321) 7-11, Nov 20, 2008Self-organized GaN nanocolumns are one-dimensional columnar nano-crystals, which have about 100nm in diameter and 1μm in height. Nanocolumns have high optical properties due to almost dislocation-free nature. And also, strong localization of light is expected in nanocolumns due to it's randomly distribution. In this study, we observed the random laser action in self-organized GaN nanocolumns for the first time. Polarization behavior, sample dependence, and theoretical approach using 2D-FDTD method will be also presented.
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IEICE technical report, 108(321) 1-6, Nov 20, 2008GaN nanocolumns have high optical properties due to dislocation-free nature. We report the fabrication of regularly arranged InGaN/GaN nanocolumns using Ti mask selective area growth technology by rf-plasma-assisted molecular-beam epitaxy (rf-MBE). The SAG of GaN nanocolumns strongly depended on the growth temperature (T_g), i.e.; at the T_g below 900℃, no SAG occurred, but above 900℃, SAG occurred. An excess value of T_g above 900℃ brought about an increased inhomogeneity in the nanocolumn shape. Uniform nanocolumn arrays were grown around the critical temperature of 900℃. A low supplied nitrogen suppressed the lateral growth of nanocolumn and the nucleation of GaN nanocrystals on the nitrided Ti thin layer. For regularly arranged InGaN/GaN nanocolumn arrays with different In composition, blue to red emissions were observed at room temperature and the PL-FWHM of those was narrower than those of self-organized nanocolumns. The ratio of PL integrated intensity at 300K to that at 4K was obtained to be 77% for a sample with 112nm diameter and 200nm period.
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Meeting abstracts of the Physical Society of Japan, 63(2) 642-642, Aug 25, 2008
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Meeting abstracts of the Physical Society of Japan, 63(1) 706-706, Feb 29, 2008
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Meeting abstracts of the Physical Society of Japan, 63(1) 736-736, Feb 29, 2008
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Meeting abstracts of the Physical Society of Japan, 63(1) 745-745, Feb 29, 2008
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Meeting abstracts of the Physical Society of Japan, 63(1) 696-696, Feb 29, 2008
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IEICE technical report, 107(253) 13-17, Oct 4, 2007GaN nanocolumns have excellent optical characteristics due to dislocation-free nature. GaN/AlGaN nanocolumn LEDs grown on n-(111) Si substrates by RF-MBE was fabricated for the first time. Clear diodes characteristics with 4.0 V of turn-on voltage and ultraviolet emission with peak-wavelength of 354nm was observed at room temperature. Although FWHM with macro-EL was 278meV, a smaller FWHM value of 119meV with micro-EL was observed. As the spatial non-uniformity in thickness and diameter of GaN MQDs may bring about the broad spectrum, the improved uniformity by nanocolumn regular-arrangement will make the narrower EL-FWHM. When Al composition of p-Al_xGa_<1-x>N was changed from 8.8 to 25.1%, the high Al content (x=25.1%) of p-AlGaN leads to narrow the FWHM as against low Al contents (x=8.8, 13.1%) due to suppress carrier overflow. The optimizations of the device sturucture, the electrode structures and the growth condition of p-type layer are needed to obtain high-performance LEDs.
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IEICE technical report, 107(253) 7-12, Oct 4, 2007The micro photoluminescence (PL) and micro time-resolved PL spectroscopy have been performed on a single InGaN/GaN nanocolumn structure grown by nitrogen plasma assisted molecular beam epitaxy. The PL spectra of single InGaN/GaN nanocolumn consist of about tens sharp emission peaks, which position does not change even if the photo-excitation carrier density increases, unlike the conventional c-plane InGaN/GaN quantum well structures (QWs). Moreover, the PL lifetime of InGaN/GaN nanocolumn is two orders of magnitude faster than that taken at the same wavelength in conventional InGaN/GaN QWs. These results suggest that the piezoelectric polarization field is suppressed in InGaN/GaN nanocolumn, and the small localized centers are formed in InGaN/GaN nanocolumn.
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Meeting abstracts of the Physical Society of Japan, 62(2) 766-766, Aug 21, 2007
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Meeting abstracts of the Physical Society of Japan, 62(2) 780-780, Aug 21, 2007
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IEICE technical report, 107(125) 29-33, Jun 22, 2007The electronic relaxation process of intersubband transition (ISBT) in semiconductor quantum wells is extremely fast due to strong electron-phonon interactions. ISBT has attracted a lot of attention as a good candidate for all-optical switching devices, because of its speed and tunability to the optical communication wavelengths of 1.2〜1.6μm. The GaN-based ISBT has the issue that owing to lattice mismatch between GaN(AlN) and the sapphire substrate, the GaN/AlN epitaxial layer exhibits high-density threading dislocations. Self-organized GaN nanocolumns are essentially free of threading dislocations, and a GaN/AlN multiple-quantum disk (MQD) can be inserted into GaN nanocolumns. Therefore, the nanocolumn-ISBT is expected to improve the switching performance. In this study, we investigated the ultrafast relaxation dynamics of ISBT at 1.55 um in GaN/AlN MQD nanocolumns using the degenerate pump probe technique at 1.55μm and confirmed the high-speed performance of the ISBT was preserved. We also estimated the saturation intensity of the nanocolumn ISBT.
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IEICE technical report, 107(124) 29-33, Jun 22, 2007The electronic relaxation process of intersubband transition (ISBT) in semiconductor quantum wells is extremely fast due to strong electron-phonon interactions. ISBT has attracted a lot of attention as a good candidate for all-optical switching devices, because of its speed and tunability to the optical communication wavelengths of 1.2〜1.6μm. The GaN-based ISBT has the issue that owing to lattice mismatch between GaN(AlN) and the sapphire substrate, the GaN/AlN epitaxial layer exhibits high-density threading dislocations. Self-organized GaN nanocolumns are essentially free of threading dislocations, and a GaN/AlN multiple-quantum disk (MQD) can be inserted into GaN nanocolumns. Therefore, the nanocolumn-ISBT is expected to improve the switching performance. In this study, we investigated the ultrafast relaxation dynamics of ISBT at 1.55 um in GaN/AlN MQD nanocolumns using the degenerate pump probe technique at 1.55μm and confirmed the high-speed performance of the ISBT was preserved. We also estimated the saturation intensity of the nanocolumn ISBT.
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Meeting abstracts of the Physical Society of Japan, 62(1) 731-731, Feb 28, 2007
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Meeting abstracts of the Physical Society of Japan, 62(1) 727-727, Feb 28, 2007
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Meeting abstracts of the Physical Society of Japan, 62(1) 672-672, Feb 28, 2007
Books and Other Publications
17Presentations
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2023 International Conference on Solod State Devices and Materials (SSDM 2023), Sep 8, 2023
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The 13th International Conference on Metamaterials, Photonic Crystals and Plasmonics (META 2023), Jul 21, 2023
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Compound Semiconductor Week 2023 (CSW2023), Jun 1, 2023
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Compound Semiconductor Week 2023 (CSW2023), May 28, 2023
Professional Memberships
6Major Research Projects
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Grants-in-Aid for Scientific Research, Japan Society for the Promotion of Science, Jun, 2019 - Mar, 2023
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戦略的な研究開発の推進 戦略的創造研究推進事業 CREST, 科学技術振興機構, 2018 - 2023
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Grants-in-Aid for Scientific Research, Japan Society for the Promotion of Science, Apr, 2017 - Mar, 2022
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Grants-in-Aid for Scientific Research, Japan Society for the Promotion of Science, Apr, 2016 - Mar, 2019
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Grants-in-Aid for Scientific Research, Japan Society for the Promotion of Science, Apr, 2012 - Mar, 2016
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Grants-in-Aid for Scientific Research, Japan Society for the Promotion of Science, Apr, 2012 - Mar, 2015
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Grants-in-Aid for Scientific Research, Japan Society for the Promotion of Science, 2009 - 2011
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Grants-in-Aid for Scientific Research, Japan Society for the Promotion of Science, 2006 - 2008
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2006 - 2008
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NEDO産業技術研究助成, 2002 - 2006
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科学研究費助成事業, 日本学術振興会, 2001 - 2002
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科学研究費助成事業, 日本学術振興会, 1999 - 2000
Industrial Property Rights
39Other
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Oct, 2006当日の授業内容に関する小テストを行って授業内容の理解度を確認している。講義時間が若干減るが、むしろ授業に対する学生の集中度が増して講義の効率が高まっている。\n小テストは採点して次回の授業で返却している。回答率の悪い問題に対しては復習を兼ねた解説を行っている。
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Apr, 2006授業(講義により頻度は異なる)において、進行速度、理解度、取り上げてほしいテーマなどを記述できるリアクションペーパを配布してその場で回収し、次回の授業計画にフィードバックしている。\n特に、学生の理解度を把握をする上で効果が高い。理解度の低いと思われる内容については次回の授業の初めに復習を行っている。
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Apr, 2006授業で使用したpdfファイルを若干の修正を行った後、学内ネットワーク上のレポート提出システムを利用して配布し、授業の復習が行いやすいように配慮している。
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Apr, 2006授業終了時に課題を与え、提出期限を次回の授業前日と設定し、次回の授業で課題の解説を行っている。\n授業時間後の復習効果が高まり、復習として効果的である。
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Apr, 2006コンピュータを用いた授業では、重要なテーマ毎に簡単な演習課題を与え、着実に理解できるような授業構成を心がけている。\n演習時にはTAが個別に対応することで、理解度の異なる学生に対しても綿密な指導ができるよう配慮している。