飛秒雷射誘發釔鋇銅氧薄膜表面週期性結構之研究

Abstract

雷射誘發材料表面週期性結構的技術已有數十年的歷史，由連續波雷射(CW laser)到飛秒雷射(femtsecond laser)都有此現象產生，但是其誘發機制仍未明確解釋，本研究中，利用不同於一般簡單金屬、半導體、絕緣體的材料─高溫超導釔鋇銅氧薄膜來進行表面週期性結構誘發，藉由不同的能量密度、脈衝數目、入射角度、偏振狀態及同時使用兩道共線且偏振互相垂直的雷射脈衝照射樣品，再將SEM影像經過二維傅立葉轉換，討論表面結構的空間週期與不同條件的關係，以期對誘發機制提供更進一步的線索。

The laser induced periodic surface structures (LIPSS) has been studied for decades. The generation of LIPSS is almost no limitations in the wavelengths and pulse durations, i.e. all of the laser sources from CW to femtosecond laser can be applied. However, the mechanism of LIPSS is still a debatable issue. In this study, we used femtosecond laser to induce periodic surface structures on the high-Tc superconductor YBCO thin films, which are different from simple metals, semiconductors and dielectrics. By adjusting the fluence, number of pulses, incident angles and the polarization of a laser beam, the LIPSS can be clearly generated on the surface of YBCO thin films and the spatial period can be analyzed through a two-dimensional Fourier transformation of the SEM images. The systematical results in this study provide further information for understanding the mechanism of the LIPSS.