Books

1.	T. Matsuoka, Y. Kangawa, Epitaxial Growth of III-Nitride Compounds: Computational Approach, Springer, 10.1007/978-3-319-76641-6, 2018.05, This book presents extensive information on the mechanisms of epitaxial growth in III-nitride compounds, drawing on a state-of-the-art computational approach that combines ab initio calculations, empirical interatomic potentials, and Monte Carlo simulations to do so. It discusses important theoretical aspects of surface structures and elemental growth processes during the epitaxial growth of III-nitride compounds. In addition, it discusses advanced fundamental structural and electronic properties, surface structures, fundamental growth processes and novel behavior of thin films in III-nitride semiconductors. As such, it will appeal to all researchers, engineers and graduate students seeking detailed information on crystal growth and its application to III-nitride compounds..
2.	Tomonori Ito, Yoshihiro Kangawa, Ab initio-Based Approach to Crystal Growth Chemical Potential Analysis, Elsevier Inc., 10.1016/B978-0-444-56369-9.00011-3, 1, 477-520, 2014.12, Computer-aided calculations for crystal growth in the area of semiconductor materials are presented from the viewpoint of an ab initio-based approach. Reliable predictions can now be made for a wide range of problems in the field of semiconductor crystal growth, such as surface reconstructions, adsorption-desorption, and migration behavior of atomic and molecular species as functions of growth conditions, by employing chemical potential analysis in ab initio calculations. The availability of chemical potential analysis is examined by investigating surface phase diagrams and growth processes on the reconstructed surfaces for prototypical semiconductors, including GaAs, InAs on GaAs, GaN, and InGaN on GaN with the aid of Monte Carlo simulations. An overview of these issues is provided and the latest achievements are presented to illustrate the capability of the ab initio-based approach by directly comparing with experimental results under realistic growth conditions, such as growth temperature and gas pressure. The successful applications in crystal growth lead to future prospects in the ab initio-based approach to the materials' design and consequently great advances in crystal growth for various materials, including nanomaterials..
3.	Takashi Nakayama, Yoshihiro Kangawa, Kenji Shiraishi, Atomic Structures and Electronic Properties of Semiconductor Interfaces, Elsevier Inc., 1, 113-174, 2011.01.

Reports

Papers

1.	Yoshihiro Kangawa, Akira Kusaba, Paweł Kempisty, Kenji Shiraishi, Shugo Nitta, Hiroshi Amano, Progress in Modeling Compound Semiconductor Epitaxy: Unintentional Doping in GaN MOVPE, Crystal Growth & Design, 10.1021/acs.cgd.0c01564, 21, 3, 1878-1890, 2021.02.
2.	Pawel Kempisty, Yoshihiro Kangawa, Evolution of the free energy of the GaN (0001) surface based on first-principles phonon calculations, PHYSICAL REVIEW B, 10.1103/PhysRevB.100.085304, 100, 085304-1-12, 2019.08.
3.	Pawel Kempisty, Yoshihiro Kangawa, Akira Kusaba, Kenji Shiraishi, Stanislaw Krukowski, Michal Bockowski, Koichi Kakimoto, Hiroshi Amano, DFT modeling of carbon incorporation in GaN(0001) and GaN(000 1 ) metalorganic vapor phase epitaxy, Applied Physics Letters, 10.1063/1.4991608, 111, 14, 2017.10, The carbon incorporation mechanism in GaN(0001) and GaN(000 1) during MOVPE was investigated using density functional theory (DFT) calculations. The results confirm that the crucial factors for carbon incorporation are Fermi level pinning and accompanying surface band bending. In addition, the lattice symmetry has a strong dependence on the stability of carbon in a few subsurface layers, which results from interactions between the impurities and surface states. It was shown that these effects are responsible for facilitating or hindering the incorporation of impurities and dopants. The influence of diluent gas species (hydrogen or nitrogen) on carbon incorporation was discussed..
4.	Y. Kangawa, H. Suetsugu, M. Knetzger, E. Meissner, K. Hazu, S. F. Chichibu, T. Kajiwara, S. Tanaka, Y. Iwasaki, K. Kakimoto, Structural and optical properties of AlN grown by solid source solution growth method, JAPANESE JOURNAL OF APPLIED PHYSICS, 10.7567/JJAP.54.085501, 54, 8, 085501-1-5, 2015.08.
5.	Y. Kangawa, A. Kusaba, H. Sumiyoshi, H. Miyake, M. Bockowski, K. Kakimoto, Real-time observation system development for high-temperature liquid/solid interfaces and its application to solid-source solution growth of AlN, APPLIED PHYSICS EXPRESS, 10.7567/APEX.8.065601, 8, 6, 065601-1-3, 2015.06.
6.	Y. Kangawa, T. Ito, A. Koukitu, K. Kakimoto, Progress in theoretical approach to InGaN and InN epitaxy: In incorporation efficiency and structural stability, JAPANESE JOURNAL OF APPLIED PHYSICS, 10.7567/JJAP.53.100202, 53, 10, 100202-1-11, 2014.10.
7.	Yoshihiro KANGAWA, Toru Akiyama, Tomonori Ito, Kenji Shiraishi, Takashi Nakayama, Surface Stability and Growth Kinetics of Compound Semiconductors: An Ab Initio-Based Approach, MATERIALS, 10.3390/ma6083309, 6, 8, 3309-3360, 2013.08, [URL], We review the surface stability and growth kinetics of III-V and III-nitride semiconductors. The theoretical approach used in these studies is based on ab initio calculations and includes gas-phase free energy. With this method, we can investigate the influence of growth conditions, such as partial pressure and temperature, on the surface stability and growth kinetics. First, we examine the feasibility of this approach by comparing calculated surface phase diagrams of GaAs(001) with experimental results. In addition, the Ga diffusion length on GaAs(001) during molecular beam epitaxy is discussed. Next, this approach is systematically applied to the reconstruction, adsorption and incorporation on various nitride semiconductor surfaces. The calculated results for nitride semiconductor surface reconstructions with polar, nonpolar, and semipolar orientations suggest that adlayer reconstructions generally appear on the polar and the semipolar surfaces. However, the stable ideal surface without adsorption is found on the nonpolar surfaces because the ideal surface satisfies the electron counting rule. Finally, the stability of hydrogen and the incorporation mechanisms of Mg and C during metalorganic vapor phase epitaxy are discussed..
8.	Yoshihiro KANGAWA, Ryutaro Toki, Tomoe Yayama, Boris M. Epelbaum, Koichi Kakimoto, Novel Solution Growth Method of Bulk AlN Using Al and Li3N Solid Sources, APPLIED PHYSICS EXPRESS, 10.1143/APEX.4.095501, 4, 9, 095501-1-095501-3, 2011.09, 窒化アルミニウムは深紫外LEDやパワーデバイス用の材料として期待されている。しかし、そのバルク成長技術は開発途上にある。本研究では、固体ソース溶液成長技術を開発し、窒化アルミニウムのバルク成長に適用した。新規溶液成長技術により、従来の窒素ガスを窒素原料とする低温溶液成長技術に比べ約２倍の成長速度を達成することに成功した。また、得られた窒化アルミニウム単結晶に含まれる貫通転位密度はハライド気相成長法により作製した単結晶と同程度であり、高品質結晶の成長が確認された。以上より、本研究で開発した固体ソース溶液成長技術の適用可能性が示唆された。.

Presentations

1.	Y. Kangawa, P. Kempisty, K. Shiraishi, Modeling and process design of III-nitride MOVPE, The 6th International Conference on Light-Emitting Devices and Their Industrial Applications, 2018.04.
2.	Y. Kangawa, Ab Initio-Based Approach to Crystal Growth of Nitride Semiconductors: Contribution of Growth Orientation and Surface Reconstruction, International Workshop on Nitride Semiconductors 2016, 2016.10, It is known that the growth process of semiconductors depends on the growth conditions such as growth temperature, partial pressures of gaseous sources, and growth orientation. To improve the crystalline quality of thin films, many experimentalist have studied the relationships between growth processes and growth conditions. A lot of technical knowledges and know-how to optimize the growth conditions have been reported. However, there is no discussion about atomistic-scale phenomena because in situ observations using electron beam is difficult in case of MOVPE and HVPE system. The knowledge of atomistic-scale phenomena is indispensable to control the growth process more precisely. Ab initio calculation is a powerful technique for modelling and analysis of atomistic-scale phenomena. The conventional ab initio calculation has been applicable to the analysis of stable surface reconstruction at absolute zero. In 2001, we proposed an ab initio-based approach that incorporates the gas-phase free energy. The theoretical approach is useful for analyzing the influence of the growth temperature and the partial pressures on the stability of the surface reconstructions. Transition of surface reconstruction on various surface orientations brings change in surface energy, i.e., change in relative stability among various surface orientations which induces facet formation. A surface phase diagram obtained by the theoretical approach is valuable in the optimization of the growth conditions and the acceleration of material development. In the present talk, I introduce how to make the surface phase diagram of nitride semiconductors by the theoretical approach..
3.	Y. Kangawa, H. Miyake, M. Bockowski, K. Kakimoto, Development of in situ observation system for liquid/solid interface during solution growth of AlN, Workshop on Ultra-Precision Processing for Wide Bandgap Semiconductors (WUPP2015), 2015.08.
4.	Y. Kangawa, K. Kakimoto, Theoretical aspects in growth of In-rich InGaN, SPIE 2015 Photonics West, 2015.02.
5.	Y. Kangawa, S. Nagata, K. Kakimoto, Microstructure of AlN/AlN(0001) grown by solid-source solution growth (3SG) method, 8th International Workshop on Bulk Nitride Semiconductors (IWBNS-VIII), 2013.10.
6.	Y. Kangawa, Influence of substrate orientation on In incorporation efficiency of InGaN grown by MOVPE -Theoretical approach on growth process/kinetics of InGaN-, 16th International Conference on MetalOrganic Vapor Phase Epitaxy (ICMOVPE-16), 2012.05.

I also hold an appointment in the Interdisciplinary Graduate School of Engineering Sciences (IGSES). I teach courses on the crystal growth of semiconductors. I educate DC and MC students to develop their ability to perform the process informatics of new materials.

I was appointed as the councilor of International and domestic scientific organizations, the editor of international journals and domestic journals, a member/chair of program committees, and organizing committees of international and domestic conferences. I collaborate with researchers in Germany, Poland, the USA, and so on. I also joined some international research projects: HORIZON 2020 "InRel-NPower 2017-2020" member, and EIG Concert-Japn "AtLv-AlGaN 2023-2025" PI..