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Synthesis of γ‐WO 3 thin films by hot wire‐CVD and investigation of its humidity sensing properties
Author(s) -
Jadkar Vijaya,
Pawbake Amit,
Waykar Ravindra,
Jadhavar Ashok,
Date Abhijit,
Late Dattatray,
Pathan Habib,
Gosavi Suresh,
Jadkar Sandesh
Publication year - 2017
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201600717
Subject(s) - materials science , crystallite , high resolution transmission electron microscopy , monoclinic crystal system , humidity , raman spectroscopy , substrate (aquarium) , tungsten , chemical vapor deposition , analytical chemistry (journal) , nanotechnology , optics , transmission electron microscopy , crystallography , crystal structure , chemistry , physics , oceanography , chromatography , geology , metallurgy , thermodynamics
In this study, monoclinic tungsten oxide (γ‐WO 3 ) have been grown in a single step using HW‐CVD method by resistively heating W filaments in a constant O 2 pressure. The formation of γ‐WO 3 was confirmed using low angle‐XRD and Raman spectroscopy analysis. Low angle‐XRD analysis revealed that as‐deposited WO 3 film are highly crystalline and the crystallites have preferred orientation along the (002) direction. HRTEM analysis and SAED pattern also show the highly crystalline nature of WO 3 with d spacing of ∼ 0.38 nm, having an orientation along the (002) direction. Surface topography investigated by SEM analysis shows the formation of a uniform and homogeneous cauliflower like morphology throughout the substrate surface without flaws and cracks. A humidity sensing device incorporating WO 3 is also fabricated, which shows a maximum humidity sensitivity factor of ∼ 3954% along with a response time of ∼14 s and a recovery time of ∼25 s. The obtained results demonstrate that it is possible to synthesize WO 3 in a single step by HW‐CVD method and to fabricate a humidity sensor by using it.