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A01 group

A01-1 Creation of Singularity Structures by Time-Domain Control under Nonequilibrium Conditions

  • Principal Investigator / Hiroshi Fujioka (The University of Tokyo / Professor)
  • Co-Investigator / Yuki Tokumoto (The University of Tokyo / Lecturer)

Accuracy of film composition control remains rather low at around one atomic layer (~1 second) The current accuracy of film composition control remains rather low at around one atomic layer (~1 s). This is because the supply of raw materials is conventionally controlled using mechanical apparatus such as a rotary motion shutter. We have developed a new crystal growth technique named “pulsed excitation deposition.” This uses electric pulses to control the supply sequence of the excited elements to the thin-film surface and has a precision of one 10 millionth of an atomic layer (~100 ns). Our novel method can be used to fabricate a range of singularity structures in single crystals under computer control. Based on the results of a microstructural analysis, we will attempt to improve the fabrication of singularity structures.

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A01-2 Creation of singularity structure by top-down method based on equilibrium condition

  • Principal Investigator / Hideto Miyake (Mie University / Professor)
  • Co-Investigator / Tsutomu Araki (Ritsumeikan University / Professor)
  • Co-Investigator / Reina Miyagawa (Nagoya Institute of Technology / Assistant Professor)

The technological development of the control of the generation of stress or threading dislocations will be carried out by a top-down method using singular structures under an equilibrium condition.
(Mie University) The effects of singularity structures, such as substrate texture, thermal annealing, and selective-area growth for the epitaxial growth of nitride semiconductors (GaN, AlN, AlGaN) will be estimated for samples fabricated by MOVPE and HVPE. Specific technologies, such as void (three-dimensional singularity structure) formation, quantum wire (one-dimensional singularity structure) fabrication and exotic atoms (zero-dimensional singularity) incorporation will be used.
(Ritsumeikan University) The control of the stress or threading dislocations by MBE with nitrogen radicals from RF plasma will be developed for forming a singularity structure at the substrate surface or in the epitaxial layer. For example, nanoscale substrate textures produced using RF plasma or a singularity interface, such as graphene, will be investigated.
(Nagoya Institute of Technology) The periodic singularity structures of the nanoscale will be formed using a femtosecond laser, and growth of the nitride semiconductors by MOVPE, HVPE, and MBE is investigated on the structures.

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A01-3 Creation of a multi-dimensional and scale singularity structure in crystals and understanding of its mechanism

  • Principal Investigator / Satoshi Kamiyama (Meijo University / Professor)
  • Co-Investigator / Tetsuya Takeuchi (Meijo University / Professor)
  • Co-Investigator / Motoaki Iwaya (Meijo University / Associate Professor)
  • Co-Investigator / Yoshio Honda (Nagoya University / Associate Professor)

In this project group, high-crystalline quality AlGaN using low-temperature deposited AlN interlayer and grooved substrate (substrate with singularity structure), high-crystalline GaInN using nano-size singularity structure, and Sb doped crystals (singularity atoms) have been realized. These intentional and control the multi-dimensional and scale singularity structure in crystals have realized the many novel devices such as world’s shortest wavelength semiconductor UV lasers, high efficiency, power UV-LEDs, and high sensitivity photosensors, and nitride-based solar cells. For further development and improvement of its novel devices, it is essential for creation of a new multi-dimensional and scale singularity structure in crystals and understanding of its mechanism.
In this project, we study the growth mechanism in the multi-dimensional and multi-scale singularity structure in crystals characterized by in situ X-ray and multi-wavelength laser beam. In addition, we invent a new singularity structure in crystal on the basis of this understanding. And, we develop the singularity structure in crystals as a new academic frontiers

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A01-4 Bottom up creation of singularities by utilization of equilibrium and non-equilibrium crystal growth from vapor phase

  • Principal Investigator / Yoshinao Kumagai (Tokyo University of Agriculture and Technology / Professor)
  • Co-Investigator / Hisashi Murakami (Tokyo University of Agriculture and Technology / Associate Professor)

Growth of stable and metastable phases of group-III wide bandgap semiconducting sesquioxides (Al2O3, Ga2O3, and In2O3) and their alloys is investigated by halide vapor phase epitaxy (HVPE). Clarification of growth conditions for the meta-stable phase is tackled by both experimentally and theoretically, which will be important knowledge of growing phase-matching alloys having wide bandgaps of 3-9 eV. In addition, two-dimensional (2D) mixed layers of stable and metastable phases are utilized to control stresses and dislocations at the hetero-interfaces by subsequent growth under the condition suitable for stable phases. Analyses of grown layers are carried out in collaboration with groups B01 and B02, and possibility of the layers in future devices is discussed with group A02.

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A01-5 Computational materials design for hetero-bond manipulation

  • Principal Investigator / Tomonori Ito (Mie University / Professor)
  • Co-Investigator / Kazumasa Hiramatsu (Mie University / Professor)
  • Co-Investigator / Toru Akiyama (Mie University / Associate Professor)
  • Co-Investigator / Takahiro Kawamura (Mie University / Assistant Professor)
  • Co-Investigator / Yoshihiro Kangawa (Kyushu University / Professor)

Computational materials design for manipulating hetero-bond as an element of singularity-structure (hereafter “the element”) is performed using various computational methods incorporating growth conditions. Utilizing surface (two-dimensional defect) and nanostructures with large surface area as a field of singularity-structure fabrication (hereafter “the field”), Ito and Akiyama (Mie University) investigate stacking and compositional modualtions, and structural transformation due to hetero-bonds appearing on “the field” as functions of growth conditions such as temperature and bean-equivalent pressure. Kangawa (Kyushu University) and Kawamura (Mie University) study incorporation process of hetero-bond into “the field” such as interface (two-dimensional defect) and dislocation (one-dimensional defect) to predict compositional fluctuation and segregation at and across the surface and the interface for processed substrate (three-dimensional defect). In the calculation procedure, ab initio-based approach combining pseudopoetntial and quantum statistical chemistry is mainly employed in addition to Monte Carlo and molecular dynamics methods. Moreover, collaborating with real-time strain analysis by Hiramatsu (Mie University), the interaction between “the element” and “the field” is clarified in terms of hetero-bond species to establish the guiding-principles for singularity structure fabrication.

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