Electrical conductivity mechanisms in zinc oxide thin films deposited by pulsed laser deposition using different growth environments

    Authors

    S. P. Heluani; G. Braunstein; M. Villafuerte; G. Simonelli;S. Duhalde

    Comments

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    Abbreviated Journal Title

    Thin Solid Films

    Keywords

    zinc oxide; electrical properties; conduction mechanisms; P-TYPE ZNO; DEVICES; Materials Science, Multidisciplinary; Materials Science, Coatings &; Films; Physics, Applied; Physics, Condensed Matter

    Abstract

    The mechanisms of electrical conduction in zinc oxide thin films, grown by pulsed laser deposition, have been investigated as a function of preparation conditions. The films were deposited on glass and silicon nitride coated silicon, using oxygen rich, oxygen deficient, or nitrogen atmospheres. The substrates were held at 473 K during deposition, and subsequently cooled down to room temperature in oxygen rich atmosphere of 4 Pa, or oxygen deficient atmosphere of 2 x 10(-3) Pa. Films deposited and cooled in an oxygen deficient atmosphere exhibited very high donor concentration, originated in intrinsic defects, and an impurity band related mechanism of conduction. Films deposited under relatively high oxygen pressure were highly resistive and showed, upon ultraviolet light irradiation, gain boundary controlled electrical transport. An enhancement of the conductivity was observed when using a nitrogen atmosphere during the deposition, and oxygen atmosphere during cooling. In this case, the dependence of the conductivity with temperature followed Mons' Law of variable range hopping, characteristic of a material with localized states randomly located in space. Since the density of hopping centers appears to be much larger than the density of nitrogen incorporated in this sample, it is suggested that the nitrogen induces defects in the zinc oxide lattice that behave as localized hopping centers, as well as carrier suppliers, giving rise to the observed conductivity. (c) 2006 Elsevier B.V. All rights reserved.

    Journal Title

    Thin Solid Films

    Volume

    515

    Issue/Number

    4

    Publication Date

    1-1-2006

    Document Type

    Article

    Language

    English

    First Page

    2379

    Last Page

    2386

    WOS Identifier

    WOS:000242931900183

    ISSN

    0040-6090

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