Presenter Profile
Masayoshi Adachi
Associate Professor
Tohoku University, Institute of Multidisciplinary Research for Advanced Material
Masayoshi Adachi is a lecturer at IMRAM, Tohoku University. His research fields include solution growth of AlN crystal and thermophysical property measurement of liquid materials using the containerless levitation technique. He obtained his Ph.D. from Gakusuin University, where he focused on research related to thermophysical property measurement using the electromagnetic levitation technique. Following the completion of his Ph.D., Masayoshi joined Prof. Fukuyama's group at Tohoku University, where he initiated his research on solution growth of AlN crystal. Currently, he is engaged in research related to surface tension and viscosity measurement of liquid materials, such as metal, sulfide, oxide, etc., utilizing the aerodynamic levitation technique.
TALK TITLE
Crystal growth behavior of AlN on Al-containing binary solutions using electromagnetic levitation and computer vision technique
KEYWORDS
solution growth of AlN, in-situ observation, thermodynamics, computer vision image processing
ABSTRACT
Aluminum nitride single crystal has a good lattice matching with AlGaN, high thermal conductivity, wide bandgap energy, high UV transparency, and high dielectric breakdown strength. Therefore, bulk AlN single crystal has a great demand for a substrate material AlGaN-based optic and electronic devices such as deep UV-LED and high-power transistors. In Prof. Fukuyama group at Tohoku University, solution growth methods of AlN crystal using Al-contained binary alloys have been developed.
To understand the growth behavior and design an optimum growth technique, an in-situ observation system for solution growth of AlN crystal using electromagnetic levitation has been developed. In this system, crystal formation behavior is recorded using high-speed camera. To consider the optimum condition of AlN growth, quantitative data is strongly beneficial. From this demand, an international and interdisciplinary research project between Prof. Fukuyama Group at Tohoku University and Prof. French group at Case Western Reserve University started. The video images analyzed in the project encompass over 530,000 single frame images. With this large dataset, analysis was done using high performance computing environment at Case Western Reserve University.
In the project, AlN formation behavior such as time changing of surface coverage and nucleation rate were quantitatively analyzed. From the results, it was clarified that nucleation and growth rates of AlN increased with increasing the driving force of AlN formation reaction, in addition, c-axis oriented AlN film formed under low growth rate conditions. Based on the results of this project, we have tried AlN growth on AlN/sapphire template using Ni-Al solution.