1.Device physics of gain-switched semiconductor lasers and solar cells

2.Many-body interactions and non-equilibrium properties of low-dimensional electron-hole systems in clean semiconductor quantumwires and wells

3.Material physics and development of high-quality semiconductor nano-structures via microscopy

4.Bioluminescence of firefly, jelly fish, sea firefly, etc. and bio/chemiluminescence measurement standards

サイズや形に依存して変化する量子力学的な物性の光学的な理解と制御を目的として、 半導体量子ナノ構造の分光手法の開発と実践に取り組んでいます。研究手法の三つの柱として、①マイクロメートル〜サブマイクロメートル空間でのレーザー分光・光学技術を開発すること、②試料の特性評価のための基礎分光を行い、新しい試料の開発に寄与すること、③測定結果に基づいたナノ構造設計と、高品質薄膜成長技術を用いた試料作製を行っています。

Advanced laser spectroscopy on the basis of lasers and microscopy is developed and applied to nanostructured semiconductor, in order to understand and control their optical properties quantum mechanically, which vary with their size and shape. We are challenging to clarify the quantized physics in semiconductor devices by follows; ①development of laser spectroscopy and optical technology in μm – sub μm space, ②spectroscopic measurement of device characteristics, ③new nanostructured design based on the experimental results and fabrication of the samples by molecular beam epitaxy growth.



Solar cells, or photovoltaic cells are the electronics devices which convert the energy of sunlight into electricity, and researches and developments aiming at achieving higher energy-conversion efficiencies have been intensively advanced. We are engaged in the elucidation of operation properties of the solar cells from the viewpoint of “Physics”. We formulated operation properties considering realistic device models and proposed design principles for improvement. In addition, we have developed a sub-cell diagnostic method based on absolute electroluminescence-efficiency measurements under LED operation for multi-junction (MJ) solar cells. Using this method, we are now studying the sub-cell properties of high-quality III-V semiconductor MJ solar cells and the degradation mechanisms of their performance by radiation-irradiation damage.



Luminous organisms harness chemical reactions in a sophisticated manner to emit light. How are excited states of light-emitting molecules prepared? What kind of chemical and physical processes underpin high efficiency of such reactions? Our challenge is to answer these questions employing state-of-the-art spectroscopy that have been developed so far in the field of material physics and optics. We are now primarily working on fireflies, jellyfish, and sea-fireflies.