飛秒雷射融蝕技術應用於硒化鋅奈米粒子之製作

Abstract

藉由飛秒雷射融蝕技術，具有六角晶系結構的硒化鋅奈米粒子可以被輕易的製備出來。在本實驗中，不同雷射能量密度可製備特定粒徑大小的奈米粒子，其大小可控制在10奈米~ 120奈米，所注入的雷射能量越大所得到的粒徑也較大。此外，值得注意的是飛秒雷射融蝕技術所製備的硒化鋅粒子有結構相轉變的現象發生，也就是由原屬立方晶系的結構轉成暫穩態六角晶系結構。其形成機制可以從熱力學的觀點解釋，由於飛秒雷射瞬間注入能量誘發龐大的融蝕壓力致使硒化鋅到達結構相轉變所需之壓力，才會由原本的穩定態結構變成暫穩態結構。藉由本研究了解奈米結構的形成機制以及其性質將有助於我們控制奈米結構的製作。

The free-standing hexagonal ZnSe nanoparticles have been successfully synthesized by femtosecond pulse laser ablation technique. We demonstrate the femtosecond laser ablation on a single crystal of ZnSe can be a simply useful method to form nanoparticles with tailored radii between ~ 10 nm to 120 nm by controlling the laser fluence. Furthermore, it is interesting to note that the fabricated ZnSe nanoparticles are metastable hexagonal phase. A picture of the growth mechanism of the metastable hexagonal phase ZnSe nanostructures will be proposed through thermodynamic point of view. Interesting, the structural phase transition is a photo-pressured triggered change from the metastable state to the stable state induced by the high peak power laser injection. It is important to note that the discussions of the nanostructure thermodynamics and stability can be applied to understand the growth mechanism of other nanostructures which are critical for optimization of the nanostructure.