We are studying materials, devices and processes relating with semiconductors, especially, silicon and silicon nanoparticles. Our goal is application of our fundamental results to society.
Theoretical limit of energy conversion efficiency for silicon solar cells is about 30%. Energy conversion efficiencies of commercial silicon solar cells are only 15~18% due to reflection at Si surfaces and recombination of electrons and holes at defects, etc. Novel chemical methods have been developed to overcome these issues.
Silicon nanoparticles possess wide band-gaps due to the quantum size effect and high activity for surface reaction. Light emitting materials, hydrogen source by reaction with water, and anode active materials for Li-ion batteries have been developed using silicon swarf as a starting material to produce Si nanopowder. We are also studying effects of the hydrogen on human body.
Semiconductor interface states have been evaluated using X-ray photoelectron spectroscopy measurements under bias developed by our group to improve silicon solar cell efficiency.