ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
Ion implantation induced dc electrical conductivity changes in polycrystalline WO3 thin films was examined. Helium, argon, and tungsten ions were implanted under the following conditions: helium at 90 keV, argon at 360 keV, and tungsten at 300 keV. The fluence range studied was from 1×1017 to 3×1017 cm−2 for helium and argon, and from 5×1014 to 5×1015 cm−2 for tungsten. The 300 K conductivities after implantation at a 1×1017 cm−2 fluence increased from ∼10−5 to ∼10−1 S cm−1 for helium implantation and to ∼102 S cm−1 for argon implantation. Also, implantation induced a broad optical absorption feature at ∼1000 nm and a negative thermopower coefficient indicating n-type conduction. The implanted samples exhibited low conductivity activation energies, which were consistent with degenerate conduction. Tungsten implantation induced conductivities were higher than those resulting from either helium or argon implantation as a conductivity of ∼102 S cm−1 was obtained at a 5×1015 cm−2 fluence. These conductivity changes are correlated to the displacements per atom resulting from the various ion implantations. Several mechanisms are responsible for the observed donor species increase: (1) in the proton case the implanted species becomes a donor, (2) in the helium and argon cases a charged oxygen vacancy may be formed by the nuclear collisions that occur during implantation, and (3) in the tungsten case the subsequent oxidation of the implanted tungsten results in the formation of a donor species. © 1998 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.368608
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