펨토초 레이저 펄스 스캔에 의한 ZnO와 GaN 표면의 나노구조 형성

Abstract

We report self-organized nanogratings formed on the surfaces of ZnO and GaN crystals by scanning a focused femtosecond laser beam at 800 nm with a repetition rate of 1 kHz. The period of the grating structure was about 600 nm on the GaN surface and about 200 nm on the ZnO surface and increased with increasing scan speed and laser pulse energy. The grating was oriented perpendicular to the direction of the linear laser's polarization. The nanogratings on the GaN surface showed metal-like characteristics due to the high plasma density while those on the ZnO surface showed dielectric-like characteristics. This could be due to the electron densities for the two surfaces being very different as a result of differences in their multiphoton absorption coefficients and internal defects, even though their band gaps were almost the same.