Defect induced structural inhomogeneity, ultraviolet light emission and near-band-edge photoluminescence broadening in degenerate In2O3 nanowires. (1st March 2018)

• Record Type: Journal Article
• Authors: Mukherjee, Souvik; Sarkar, Ketaki; Wiederrecht, Gary P; Schaller, Richard D; Gosztola, David J; Stroscio, Michael A; Dutta, Mitra
• Is Part Of: Nanotechnology. Volume 29:Number 17(2018)
• Publication Date: 2018-03-01
• Subjects: indium oxide -- nanowires -- vapor–liquid–solid method -- defects -- near-band-edge emission -- degenerate -- photoluminesence broadening; Nanotechnology -- Periodicals; Nanotechnology -- Periodicals; Nanotechnology; Publications périodiques; Nanotechnologies; Periodicals; 620.5
• DOI: 10.1088/1361-6528/aaaf34
• Languages: English
• ISSNs: 0957-4484

Abstract

Abstract: We demonstrate here defect induced changes on the morphology and surface properties of indium oxide (In2 O3 ) nanowires and further study their effects on the near-band-edge (NBE) emission, thereby showing the significant influence of surface states on In2 O3 nanostructure based device characteristics for potential optoelectronic applications. In2 O3 nanowires with cubic crystal structure (c-In2 O3 ) were synthesized via carbothermal reduction technique using a gold-catalyst-assisted vapor–liquid–solid method. Onset of strong optical absorption could be observed at energies greater than 3.5 eV consistent with highly n-type characteristics due to unintentional doping from oxygen vacancy ( V O ) defects as confirmed using Raman spectroscopy. A combination of high resolution transmission electron microscopy, x-ray photoelectron spectroscopy and valence band analysis on the nanowire morphology and stoichiometry reveals presence of high-density of V O defects on the surface of the nanowires. As a result, chemisorbed oxygen species can be observed leading to upward band bending at the surface which corresponds to a smaller valence band offset of 2.15 eV. Temperature dependent photoluminescence (PL) spectroscopy was used to study the nature of the defect states and the influence of the surface states on the electronic band structure and NBE emission has been discussed. Our data reveals significant broadening of the NBE PL peak consistent with impurity band broadening leading to band-tailing effect from heavy doping.