Please use this identifier to cite or link to this item: http://hdl.handle.net/10397/6022
Title: Relationship between the microstructure and nanoindentation hardness of thermally evaporated and magnetron-sputtered electrochromic tungsten oxide films
Authors: Ong, CW 
Wong, HY
Pang, GKH
Baba-Kishi, KZ
Choy, CL
Keywords: Amorphous films
Atomic force microscopy
Crystal microstructure
Crystalization
Densification
Elastic moduli
Evaporation
Grain size and shape
High temperature effects
Indentation
Magnetron sputtering
Microhardness
Oxygen
Polycrystalline materials
X ray diffraction analysis
X ray photoelectron spectroscopy
Issue Date: Jun-2001
Publisher: Cambridge University Press
Source: Journal of materials research, June 2001, v. 16, no. 06, p. 1541-1548 How to cite?
Journal: Journal of materials research 
Abstract: Tungsten oxide (WOₓ) films were fabricated by (i) reactive thermal evaporation (RTE) at room temperature with oxygen ambient pressure Pₒ₍₂₎ as a parameter, and (ii) reactive magnetron sputtering (RMS) with substrate temperature T[sub s] as a parameter. The film structure revealed by x-ray photoelectron spectroscopy, x-ray diffraction, density measurements, infrared absorption, and atomic force microscopy was correlated with the nanoindentation hardness H. The RTE WOₓ films deposited at high Pₒ₍₂₎ were amorphous and porous, while H depended appreciably on normalized penetration depth h[sub D] (indentation depth/film thickness) due to the closing of the pores at the point of indentation. Decrease in Pₒ₍₂₎ from 10 to 2 × 10⁻³ retort led to smaller porosity, weaker h[sub D] dependence of H, and higher average H (measured at h[sub D] ≈ 0.2 to 0.3, for example). The RMS WOₓ film deposited at room temperature was amorphous and denser than all RTE films. The rise in substrate temperature T[sub s] first densified the film structure (up to 110 °C) and then induced crystallization with larger grain size for T[sub s] ≥ 300 °C. Correspondingly, the h D dependence of H became weaker. In particular, H of the RMS sample deposited at 110 °C showed a peak at h[sub D] slightly above 1 owing to pileup at the contact point of indentation. For higher T[sub s], pileup occurred at shallower h[sub D] and the average H (measured at h[sub D] ≈ 0.2 to 0.3, for example) rose, accompanied by the increase of grain size.
URI: http://hdl.handle.net/10397/6022
ISSN: 0884-2914
EISSN: 2044-5326
DOI: 10.1557/JMR.2001.0214
Rights: © 2001 Materials Research Society
The following article "C. W. Ong, H. Y. Wong, G. K. H. Pang, K. Z. Baba-Kishi and C. L. Choy (2001). Relationship between the microstructure and nanoindentation hardness of thermally evaporated and magnetron-sputtered electrochromic tungsten oxide films. Journal of Materials Research, 16(6), p. 1541-1548. doi:10.1557/JMR.2001.0214." is available at http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=7998492
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