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Superior functionality by design: Selective ozone sensing realized by rationally constructed high-index ZnO surfaces

: Güder, F.; Yang, Y.; Menzel, A.; Wang, C.Y.; Danhof, J.; Subannajui, K.; Hartel, A.; Hiller, D.; Kozhummal, R.; Ramgir, N.; Cimalla, V.; Schwarz, U.T.; Zacharias, M.


Small 8 (2012), No.21, pp.3307-3314
ISSN: 1613-6810
Journal Article
Fraunhofer IAF ()

A new technique is reported for the transformation of smooth nonpolar ZnO nanowire surfaces to zigzagged high-index polar surfaces using polycrystalline ZnO thin fi lms deposited by atomic layer deposition (ALD). The c-axis-oriented ZnO nanowires with smooth nonpolar surfaces are fabricated using vapor deposition method and subsequently coated by ALD with a ZnO particulate thin film. The synthesized ZnO-ZnO core-shell nanostructures are annealed at 800 °C to transform the smooth ZnO nanowires to zigzagged nanowires with high-index polar surfaces. Ozone sensing response is compared for all three types of fabricated nanowire morphologies, namely nanowires with smooth surfaces, ZnO-ZnO core-shell nanowires, and zigzagged ZnO nanowires to determine the role of crystallographic surface planes on gas response. While the smooth and core-shell nanowires are largely non-responsive to varying O(3) concentrations in the experiments, zigzagged nanowires show a signifi cantly higher sensitivity (ppb level) owing to inherent defectrich high-index polar surfaces.