Formation mechanism of self-assembled polarization-dependent periodic nanostructures in β-Ga2O3

Y. Nakanishi; Y. Shimotsuma; M. Sakakura; M. Shimizu; K. Miura

doi:10.1117/12.2288276

19 February 2018 Formation mechanism of self-assembled polarization-dependent periodic nanostructures in β-Ga₂O₃

Y. Nakanishi, Y. Shimotsuma, M. Sakakura, M. Shimizu, K. Miura

Proceedings Volume 10520, Laser-based Micro- and Nanoprocessing XII; 105201J (2018) https://doi.org/10.1117/12.2288276
Event: SPIE LASE, 2018, San Francisco, California, United States

Abstract

We have successfully observed self-assembled periodic nanostructures inside Si single crystal and GaP crystal, by the femtosecond double-pulse irradiation. These results experimentally indicate that the self-assembly of the periodic nanostructures inside semiconductors triggered by ultrashort pulses irradiation are possibly associated with a direct or an indirect band gap. More recently we have also empirically classified the photoinduced bulk nanogratings into the following three types: (1) structural deficiency, (2) compressed structure, (3) partial crystallization. We have still a big question about what material properties are involved in the bulk nanograting structure formation. In this study, to expand the selectivity of the material for bulk nanograting formation, we have employed β-Ga₂O₃ crystals (indirect bandgap Eg ~ 4.8 eV) as a sample for femtosecond laser irradiation. The nanograting structure inside β-Ga₂O₃ crystal was aligned perpendicular to the laser polarization direction. Such phenomenon is similar to the nanograting in SiO₂ glass (Eg ~ 9 eV). Moreover, to clarify the band structure, we have also investigate the photoinduced structure in Sn doped β-Ga₂O₃ crystals, which exhibit direct bandgap according to the first principle calculation.

Citation Download Citation

Y. Nakanishi, Y. Shimotsuma, M. Sakakura, M. Shimizu, and K. Miura "Formation mechanism of self-assembled polarization-dependent periodic nanostructures in β-Ga₂O₃", Proc. SPIE 10520, Laser-based Micro- and Nanoprocessing XII, 105201J (19 February 2018); https://doi.org/10.1117/12.2288276

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