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HL: Halbleiterphysik

HL 17: Poster Ib

HL 17.18: Poster

Freitag, 4. März 2005, 16:30–19:00, Poster TU F

Evidence for an electrically conducting layer at the native zinc oxide surface — •Oliver Schmidt¹, Arnd Geis¹, Peter Kiesel¹, Noble Johnson¹, Andreas Waag², and Gottfried Döhler³ — ¹Palo Alto Research Center, 3333 Coyote Hill Rd., Palo Alto, CA 94304, USA — ²University of Braunschweig, Institute for Semiconductor Technology, Hans-Sommer Str. 66, 38106 Braunschweig — ³University of Erlangen, Institute for Technical Physics I, Erwin Rommel-Str. 1, 91058 Erlangen

Measurements of the electrical properties of high-resistivity zinc oxide (ZnO) are strongly influenced by the sample ambient. Temperature-dependent Hall-effect measurements were performed on Li- and Cu-doped bulk crystals in both air and vacuum. Repeating the measurements under a given test ambient produced stable results. Changing the ambient systematically changed the measured results. We explain this behavior in terms of a surface conducting channel that exists in vacuum but is destroyed upon exposure to air. We propose that the surface conducting layer is eliminated in air due to changes of the surface condition (i.e., molecular adsorption from the gas phase and/or surface reconstruction mechanisms).