title: The study of optical band edge property of bismuth oxide nanowires α-Bi2O3.
abstract: 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.
authors.affiliation: Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei 106, Taiwan.
authors.forename: Ching-Hwa
authors.initials: CH
authors.lastname: Ho
authors.forename: Ching-Hsiang
authors.initials: CH
authors.lastname: Chan
authors.forename: Ying-Sheng
authors.initials: YS
authors.lastname: Huang
authors.forename: Li-Chia
authors.initials: LC
authors.lastname: Tien
authors.forename: Liang-Chiun
authors.initials: LC
authors.lastname: Chao
mesh_terms: D001729:Bismuth / Q000737:chemistry*; D008163:Luminescent Measurements / Q000379:methods*; D008422:Materials Testing; D053770:Nanowires / Q000737:chemistry* / Q000648:ultrastructure*
chemical_list: C033301:bismuth oxide; D001729:Bismuth