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Title: VO 2 thin films synthesis for collaborators and various applications.

Abstract

Vanadium dioxide (VO 2) is an attractive material for a variety of applications due to its metal-to-insulator transition (MIT) observed at modest temperatures. This transition takes VO 2 from its low temperature insulating monoclinic phase to a high temperature (above 68°C) metallic rutile phase. This transition gives rise to a change in resistivity up to 5 orders of magnitude and a change in complex refractive index (especially at IR wavelengths), which is of interest for radar circuit protection and tunable control of infrared signature. Recently, collaborations have been initiated between CINT scientists and external university programs. The Enhanced Surveillance funds help fund this work which enabled synthesis of VO 2 films for several collaborations with internal and external researchers.

Authors:
 [1];  [1]
  1. Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1331870
Report Number(s):
SAND-2016-11308R
648935
DOE Contract Number:
AC04-94AL85000
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Johnson, Raegan Lynn, and Clem, Paul G. VO2 thin films synthesis for collaborators and various applications.. United States: N. p., 2016. Web. doi:10.2172/1331870.
Johnson, Raegan Lynn, & Clem, Paul G. VO2 thin films synthesis for collaborators and various applications.. United States. doi:10.2172/1331870.
Johnson, Raegan Lynn, and Clem, Paul G. Tue . "VO2 thin films synthesis for collaborators and various applications.". United States. doi:10.2172/1331870. https://www.osti.gov/servlets/purl/1331870.
@article{osti_1331870,
title = {VO2 thin films synthesis for collaborators and various applications.},
author = {Johnson, Raegan Lynn and Clem, Paul G.},
abstractNote = {Vanadium dioxide (VO2) is an attractive material for a variety of applications due to its metal-to-insulator transition (MIT) observed at modest temperatures. This transition takes VO2 from its low temperature insulating monoclinic phase to a high temperature (above 68°C) metallic rutile phase. This transition gives rise to a change in resistivity up to 5 orders of magnitude and a change in complex refractive index (especially at IR wavelengths), which is of interest for radar circuit protection and tunable control of infrared signature. Recently, collaborations have been initiated between CINT scientists and external university programs. The Enhanced Surveillance funds help fund this work which enabled synthesis of VO2 films for several collaborations with internal and external researchers.},
doi = {10.2172/1331870},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Nov 01 00:00:00 EDT 2016},
month = {Tue Nov 01 00:00:00 EDT 2016}
}

Technical Report:

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  • Amorphous films of vanadium dioxide were prepared by the thermal decomposition of vanadium acetylacetonate in a CO/CO/sub 2/ atmosphere. Films were deposited on glass and quartz.
  • A new chemical and chemical/ultrasonic approach to the preparation of VO{sub 2} films and VO{sub 2}-impregnated bulk materials has been developed. In this approach, a V{sub 2}O{sub 5} sol prepared by quenching is used to coat SiO{sub 2} substrates. The resulting gel-film is heat treated in a reducing atmosphere to form a film identified as VO{sub 2} from the results of X-ray diffraction and both optical and resistivity measurements, which reveal the phase transition characteristic of vanadium dioxide. The advantage of this approach to the formation of VO{sub 2} is that the V{sub 2}O{sub 5} sol can be used tomore » impregnate porous materials, which are then heated treated to form an optically active composite material. The switching properties of the VO{sub 2} films are investigated using optical and resistivity measurements, and the results are compared to those obtained for VO{sub 2}-films prepared by more-conventional methods.« less
  • Sputtered films have been formed with two improved composite (Si + CdAs/sub 2/) targets. Near stoichiometric and mechanically continuous CdSiAs/sub 2/ films have been formed on metal substrates. Films of this type will be used over the next reporting period for heterojunction formation. Evaporation studies related to CdAs/sub 2/ have been completed. Stoichiometric CdAs/sub 2/ films could not be formed by means of single-source evaporation of CdAs/sub 2/ bulk. Hence, this dual source approach (Si + CdAs/sub 2/) does not appear feasible with the techniques used thus far. Electron beam microprobe elemental analysis has been improved by changing from amore » GaAs standard to one of SiAs. The latter standard is more directly applicable to the compounds being measured. Accuracy of elemental composition measurements by means of the microprobe are estimated to be about +- 0.1 atomic percent. A CdS/CdSiAs/sub 2/ junction was formed on bulk CdSiAs/sub 2/. This junction gives a good diode curve (no shunting or series resistance problems), although very poor photovoltaic response. Heterojunction formation and gridding procedure have been established.« less
  • Thin film growth using the single target sputtering system was concluded. The best CdSiAs/sub 2/ films were obtained from a composite target (CdAs/sub 2/ + Si), followed by post-deposition reactive heat treatments. The new Perkin-Elmer Randex 2400 8J multi-target sputtering system was installed. A variety of problems arose, which prevented any meaningful runs from being performed with that system over this reporting period. These problems were related to the J-arm, the RF power generator, RF shielding, water cooling, target switches, substrate bias network, vacuum gage controller, graphite heater elements and RF impedance matching network. These problems have been largely corrected.more » Improvements were made in the magnetic field (van der Pauw), spectral response and variable temperature measurements facilities.« less
  • Early problems associated with the Randex multi-target sputtering unit were rectified. CdAs/sub 2/, Si and Cd targets were obtained from commercial vendors. Runs have been made using CdAs/sub 2/ and Si targets separately. The CdAs/sub 2/ deposition rate falls off rapidly with increasing substrate temperature, but the compositions remain nearly stoichiometric. Dual target runs were performed with CdAs/sub 2/ and Si targets. Films on 7059 substrates are amorphous, with composition depending strongly on sputtering parameters. A dual target run made on polished GaAs targets resulted in a crystalline film, although of low Si composition. CdSiAs/sub 2/ (211) and (112) peaksmore » were identified in the x-ray spectrum. Additional problems with the Randex unit precluded further runs in that system.« less