Frontier Research Institute for Interdisciplinary Sciences
Tohoku University

Our research aim is the realization of high performance functional optical devices based on wide-bandgap semiconductors. For developing novel devices that overtake conventional ones, not only advanced crystal growth techniques but also proposals of appropriate device structures that utilize their attractive material properties are indispensable.

　Nitride semiconductors, one of the wide-bandgap semiconductor members, have been spread all the world over as blue and white LEDs and laser diodes. In addition to nitride semiconductors such as gallium nitride (GaN), oxide semiconductors such as zinc oxide (ZnO) are also classified as a wide bandgap semiconductor. Both nitride and oxide semiconductors have large exciton binding energies, indicating that excitons in such wide-bandgap semiconductors are stable at room temperature. By using novel crystal growth techniques, such a material talent can be exploited in device structures.

　Device structures referred to here are microcavities, which enable semiconductors to control light-matter interactions artificially. Based on these, we challenge the implementation of wide-bandgap semiconductor crystals, grown by our novel growth techniques, into microcavities. Our research leads high performance functional optical devices, of which qualities are not dominated by non-radiative recombination ratios due to crystal defects.