Femtosecond‐Laser Irradiation onto Sapphire Substrates in an N₂ Ambient Atmosphere

Abstract

Herein, a new technique is proposed for forming nitrogen‐related bonds anywhere on a substrate using a femtosecond laser. Laser‐induced periodic structures with a minimum periodicity of <50 nm are formed on a sapphire substrate. Nitrogen‐related bonds are formed at the sapphire surface by laser irradiation in N2 ambient. This technique is applicable to periodic polarization inversion in nitride semiconductors for nonlinear optical devices.

Formation of femtosecond laser-induced periodic nanostructures on GaN

“…Here, the LIPSSs on 6H-SiC, which has a bandgap close to that of GaN, were crystalline without disturbances in crystalline orientation from the substrate, 3) while the LIPSSs on sapphire showed a similar disturbance in crystalline orientation. 32) In future work, we must come to better understand the material properties that cause these crystalline states in the LIPSSs and must determine the stage in LIPSS formation when these states are generated.…”

Periodicity control of laser-induced periodic nanostructures by thin deposition layer on sapphire substrate

“…The parameter of the laser irradiation such as power were decided based on our previous research which formed LIPSS on sapphire substrates. 22) As for the deposition layers with different dielectric constants, for the purpose of this research we chose Pt-Pd and ZnO to be deposited onto the sapphire substrate. Pt-Pd was deposited by magnetron cathode spattering (SC-701C-MC, Sanyu Electron), 23) and ZnO by radio-frequency magnetron spattering (L-250S-FH, ANELVA) 24) accordingly.…”