Epitaxial growth and properties of MoOx(2

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Publication Type	Journal Article
School or College	College of Engineering
Department	Materials Science & Engineering
Creator	Tiwari, Ashutosh
Other Author	Bhosle, V.; Narayan, J.
Title	Epitaxial growth and properties of MoOx(2<x<2.75) films
Date	2005
Description	We report the growth of epitaxial molybdenum oxide (MoOx,2<x<2.75) films on c plane of sapphire substrate using pulsed laser deposition in oxygen environment. The structure was characterized using x-ray diffraction, high resolution transmission electron microscopy and x-ray photoelectron spectroscopy (XPS). Electrical resistivity and optical properties were investigated using four-point-probe resistivity measurements and spectroscopy techniques, respectively. It was found that the film had a monoclinic structure based on MoO2 phase and showed an unusual combination of high conductivity and high transmittance in the visible region after annealing. The unusual combination of these properties was realized by systematically controlling the relative fraction of different oxidation states of molybdenum, namely Mo4+, Mo5+, and Mo6+ in the monoclinic phase. For a film 60 nm thick and annealed at 250 °C for 1 h, the ratio of Mo6+ / (Mo4++Mo5+) was determined to be ~2.9/1 using XPS, and a typical value of transmittance was ~65% and resistivity close to 1310−3 Ω cm. These results demonstrate growth of epitaxial MoOx films with tunable electrical and optical properties. Further optimization of these properties is expected to result in applications related to display panels, solar cells, chromogenic (photochromic, electrochromic, gasochromic) devices, and transparent conducting oxides. Our ability to grow epitaxial MoOx films can further aid their integration with optoelectronic and photonic devices.
Type	Text
Publisher	American Institute of Physics (AIP)
Journal Title	Journal of Applied Physics
Volume	97
Issue	8
First Page	83539
DOI	10.1063/1.1868852
citatation_issn	218979
Subject	Epitaxy; MoO
Subject LCSH	Metal oxide semiconductors; Zinc oxide; Thin films; Epitaxy; Semiconductor doping
Language	eng
Bibliographic Citation	Bhosle, V., Tiwari, A., & Narayan, J. (2005). Epitaxial growth and properties of MoOx(2<x<2.75) films. Journal of Applied Physics, 97(8), 083539.
Rights Management	(c)American Institute of Physics. The following article appeared in Bhosle, V., Tiwari, A., & Narayan, J., Journal of Applied Physics, 97(8), 2005 and may be found at http://dx.doi.org/10.1063/1.1868852
Format Medium	application/pdf
Format Extent	664,306 bytes
Identifier	ir-main,12066
ARK	ark:/87278/s6r78zxg
Setname	ir_uspace
ID	707102
Reference URL	https://collections.lib.utah.edu/ark:/87278/s6r78zxg

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We report the growth of epitaxial molybdenum oxide (MoOx,2<x<2.75) films on c plane of sapphire substrate using pulsed laser deposition in oxygen environment. The structure was characterized using x-ray diffraction, high resolution transmission electron microscopy and x-ray photoelectron spectroscopy (XPS). Electrical resistivity and optical properties were investigated using four-point-probe resistivity measurements and spectroscopy techniques, respectively. It was found that the film had a monoclinic structure based on MoO2 phase and showed an unusual combination of high conductivity and high transmittance in the visible region after annealing. The unusual combination of these properties was realized by systematically controlling the relative fraction of different oxidation states of molybdenum, namely Mo4+, Mo5+, and Mo6+ in the monoclinic phase. For a film 60 nm thick and annealed at 250 °C for 1 h, the ratio of Mo6+ / (Mo4++Mo5+) was determined to be ~2.9/1 using XPS, and a typical value of transmittance was ~65% and resistivity close to 1310−3 Ω cm. These results demonstrate growth of epitaxial MoOx films with tunable electrical and optical properties. Further optimization of these properties is expected to result in applications related to display panels, solar cells, chromogenic (photochromic, electrochromic, gasochromic) devices, and transparent conducting oxides. Our ability to grow epitaxial MoOx films can further aid their integration with optoelectronic and photonic devices.