Ho Ching-Hwa, Chan Ching-Hsiang, Huang Ying-Sheng, Tien Li-Chia, Chao Liang-Chiun
Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei 106, Taiwan.
Opt Express. 2013 May 20;21(10):11965-72. doi: 10.1364/OE.21.011965.
The α-phase Bi(2)O(3) (α-Bi(2)O(3)) is a crucial and potential visiblelight photocatalyst material needless of intentional doping on accommodating band gap. The understanding on fundamental optical property of α-Bi(2)O(3) is important for its extended applications. In this study, bismuth oxide nanowires with diameters from tens to hundreds nm have been grown by vapor transport method driven with vapor-liquid-solid mechanism on Si substrate. High-resolution transmission electron microscopy and Raman measurement confirm α phase of monoclinic structure for the as-grown nanowires. The axial direction for the as-grown nanowires was along < 122 >. The band-edge structure of α-Bi(2)O(3) has been probed experimentally by thermoreflectance (TR) spectroscopy. The direct band gap was determined accurately to be 2.91 eV at 300 K. Temperaturedependent TR measurements of 30-300 K were carried out to evaluate temperature-energy shift and line-width broadening effect for the band edge of α-Bi(2)O(3) thin-film nanowires. Photoluminescence (PL) experiments at 30 and 300 K were carried out to identify band-edge emission as well as defect luminescence for the α-Bi(2)O(3) nanowires. On the basis of experimental analyses of TR and PL, optical characteristics of direct band edge of α-Bi(2)O(3) nanowires have thus been realized.
α相Bi₂O₃（α - Bi₂O₃）是一种关键且有潜力的可见光光催化剂材料，无需进行有意掺杂来调节带隙。了解α - Bi₂O₃的基本光学性质对其扩展应用很重要。在本研究中，通过气 - 液 - 固机制驱动的气相传输法在硅衬底上生长出了直径从几十到几百纳米的氧化铋纳米线。高分辨率透射电子显微镜和拉曼测量证实了所生长纳米线为单斜结构的α相。所生长纳米线的轴向沿<122>方向。通过热反射（TR）光谱对α - Bi₂O₃的带边结构进行了实验探测。在300 K时准确测定直接带隙为2.91 eV。进行了30 - 300 K的温度相关TR测量，以评估α - Bi₂O₃薄膜纳米线带边的温度 - 能量移动和线宽展宽效应。在30 K和300 K下进行了光致发光（PL）实验，以识别α - Bi₂O₃纳米线的带边发射以及缺陷发光。基于TR和PL的实验分析，从而实现了α - Bi₂O₃纳米线直接带边的光学特性。
