Microstructure of epitaxial VO[sub 2] thin films deposited on (11[bar 2]0) sapphire by MOCVD

Journal Article · Thu Sep 01 00:00:00 EDT 1994 · Journal of Materials Research; (United States)

DOI:https://doi.org/10.1557/JMR.1994.2264· OSTI ID:7039903

Zhang, H; Chang, H L.M.; Guo, J; Zhang, T J ^[1]

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1. Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439-4838 (United States)

Epitaxial VO[sub 2] thin films grown on (11[bar 2]0) sapphire ([alpha]--Al[sub 2]O[sub 3]) substrates by MOCVD at 600 [degree]C have been characterized by conventional electron microscopy and high resolution electron microscopy (HREM). Three different epitaxial relationships between the monoclinic VO[sub 2] films and sapphire substrates have been found at the room temperature: (I) (200)[010] monoclinic VO[sub 2]//(11[bar 2]0)[0001] sapphire; (II) (002)[010] monoclinic VO[sub 2]//(11[bar 2]0)[0001] sapphire; and (III) (020)[102] monoclinic VO[sub 2]//(11[bar 2]0)[0001] sapphire. Epitaxial relationships II and III are equivalent to each other when the film possesses tetragonal structure at the deposition temperature: i.e., they can be described as (010)[100] tetragonal VO[sub 2]//(11[bar 2]0)[0001] sapphire and (100)[010] tetragonal VO[sub 2]//(11[bar 2]0)[0001] sapphire. HREM image shows that the initial nucleation of the film was dominated by the first orientation relationship, but the film then grew into the grains of the second and the third (equivalent to each other at the deposition temperature) epitaxial relationships. Successive 90[degree] transformation rotational twins around the [ital a]-axis are commonly observed in the monoclinic films.

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 7039903
• Journal Information: Journal of Materials Research; (United States), Vol. 9:9; ISSN 0884-2914
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
VANADIUM OXIDES
EPITAXY
CHEMICAL VAPOR DEPOSITION
ELECTRON MICROSCOPY
MICROSTRUCTURE
NUCLEATION
SAPPHIRE
TEMPERATURE RANGE 0273-0400 K
TEMPERATURE RANGE 0400-1000 K
THIN FILMS
CHALCOGENIDES
CHEMICAL COATING
CORUNDUM
DEPOSITION
FILMS
MICROSCOPY
MINERALS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
SURFACE COATING
TEMPERATURE RANGE
TRANSITION ELEMENT COMPOUNDS
VANADIUM COMPOUNDS
360202* - Ceramics
Cermets
& Refractories- Structure & Phase Studies