利用脈衝雷射剝鍍法成長鋯鈦酸鉛奈米線之研究

Abstract

摘要

本研究主要是探討利用脈衝雷射剝鍍(Pulsed laser deposition or PLD)的方法，在單晶鈦酸鍶(SrTiO3 or STO)基板上成長鋯鈦酸鉛(PbZrxTi(1-x)O3 or PZT)奈米線的機制以及其結構。本實驗乃是第一個利用PLD的方式長成PZT奈米線，在PZT的研究當中，我們並不需要先行在基板上塗上催化劑便可長出PZT奈米線，為了辨別PZT奈米線成長的方式為何，我們設計了不同的實驗參數，利用SEM我們可以觀察到在不同參數下PZT奈米線不同的表面形貌，例如不同的PZT奈米線呈現的長度、寬度、以及密度等等的差異，搭配TEM的觀察，我們可以推測PZT奈米線的成長乃是屬於VS的成長模式。 而另外我們引入了不同方向的鈦酸鍶基板來成長PZT奈米線，發現PZT奈米線成長的方向會與鈦酸鍶基板方向有相當的一致性，因此利用基板方向的改變我們可以在基板上形成可以控制角度且方向高度一致的PZT奈米線。

ABSTRACT

Lead zirconate titanate (PZT) is one of the most promising materials with large piezoelectric constants. In this study, we demonstrate the first epitaxial growth of PbZrxTi(1-x)O3 ¬(PZT) nanowire arrays by Pulsed laser deposition (PLD). Catalyst free growth of PZT nanowires by PLD was carried out on single crystal SrTiO3 (STO) substrates. After the PZT deposition, specimens were analyzed using X-ray diffractometry (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The nanowires have been confirmed as crystalline perovskite PZT by X-ray diffraction. Scanning electron microscopy and transmission electron microscopy reveal that a thin wetting layer in epitaxy with the SrTiO3 substrate is formed first, followed by pyramids and nanowires. The nucleation of nanowires occurs either directly at the interface, or later on top of some of the pyramids, suggesting various nucleation mechanisms. In addition, (100) oriented PZT nanowires were epitaxially grown on (100), (110), and (111) oriented STO substrates, allowing the limited growth directions. Arrays of well-aligned, direction controlable nanowires were obtained with uniform lengths and diameters. This feasibility of PLD for fabricating PZT nanowires would contribute to incorporating the rich functionalities of various transition metal oxides into nanowires via in situ construction of heterostructures in oxide nanowires.