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Mechanism of insulator-to-metal transition in heavily Nb doped anatase TiO2
J Tao1; H Pan2; LM Wong1; TI Wong1; JW Chai1; J Pan1; SJ Wang1
2014
Source PublicationMATERIALS RESEARCH EXPRESS
ISSN2053-1591
Volume1Issue:1
Abstract

Heavily Nb-doped anatase TiO2 (TNO) thin films were prepared by pulsed dc magnetron sputtering using an Nb-doped TiO2 target. The as-grown films exhibit high resistivity whose resistance decreases by similar to 2x10(4)-fold upon vacuum annealing. The similar to 40% Nb-doped anatase TiO2 film shows a low resistivity of 5.7 x 10(-4) Omega cm and a high electron concentration of 3.07 x 10(21) cm(-3). Combined in situ x-ray photoelectron spectroscopy (XPS) measurement and density-functional theory (DFT) calculations show that oxygen interstitial (O-int) and Nb interstitial (Nb-int) defect clusters introduce localized shallow p-type accepter states that trap the electrons and reduce the conductivity. These defect clusters can be eliminated by vacuum annealing which is companied by outward diffusion of Nb. As a result, the trapped electrons backfill the Ti sites which are delocalized to promote conductivity.

KeywordTransparent Conducting Oxide Density-functional Theory X-ray Photoelectron Spectroscopy Nb-doped Anatase Tio2
DOI10.1088/2053-1591/1/1/015911
Indexed BySCIE
Language英語English
WOS Research AreaMaterials Science
WOS SubjectMaterials Science, Multidisciplinary
WOS IDWOS:000209665100084
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Cited Times [WOS]:7   [WOS Record]     [Related Records in WOS]
Document TypeJournal article
CollectionFaculty of Science and Technology
INSTITUTE OF APPLIED PHYSICS AND MATERIALS ENGINEERING
Affiliation1.Inst Mat Sci & Engn, 3 Res Link, Singapore 117602, Singapore
2.Univ Macau, Fac Sci & Technol, Macau, Peoples R China
Recommended Citation
GB/T 7714
J Tao,H Pan,LM Wong,et al. Mechanism of insulator-to-metal transition in heavily Nb doped anatase TiO2[J]. MATERIALS RESEARCH EXPRESS,2014,1(1).
APA J Tao,H Pan,LM Wong,TI Wong,JW Chai,J Pan,&SJ Wang.(2014).Mechanism of insulator-to-metal transition in heavily Nb doped anatase TiO2.MATERIALS RESEARCH EXPRESS,1(1).
MLA J Tao,et al."Mechanism of insulator-to-metal transition in heavily Nb doped anatase TiO2".MATERIALS RESEARCH EXPRESS 1.1(2014).
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