飛秒雷射誘發表面週期結構及奈米粒子之研究

Abstract

本論文分成兩個部分，第一部分為利用飛秒雷射誘發高溫超導釔鋇銅氧(YBCO)薄膜微橋表面之週期性波紋結構，藉由不同能量密度和偏振方向的飛秒雷射脈衝，以控制YBCO微橋上週期性波紋結構的性質與方向。此外，我們進一步量測及分析表面週期性波紋結構對傳輸特性之影響。第二部分則是利用飛秒雷射由本立方晶系結構的硒化鋅(ZnSe)單晶製備六角晶系(hexagonal)結構的奈米顆粒，藉由不同的能量密度，可控制ZnSe奈米顆粒之粒徑大小。此外，對於粒徑較小且分布均勻之ZnSe奈米顆粒，我們可以在拉曼光譜中觀察到較強的表面模態。

There are two parts in this thesis. For the first part, the laser induced periodic surface structures (LIPSSs) have been s produced on the high-Tc superconductor YBa2Cu3O7-δ (YBCO) microbridges by irradiating femtosecond laser pulses. By adjusting the fluences, and the polarization of a laser beam, the properties and direction of LIPSSs can be controlled on the surface of YBCO microbridges, which were examined through SEM images. Moreover, the LIPSS-dependent transport properties of laser irradiated YBCO microbridges are measured and discussed. For the second part, the wurtzite phase ZnSe nanoparticles were prepared from zincblende ZnSe single crystal using femtosecond pulse laser ablation. By controlling the laser fluences, the average size of ZnSe nanoparticles can be varied. In Raman spectra, the surface phonon mode becomes dominant in the smaller average particle size with uniform size distribution.