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Keywords:

  • ZnAlO;
  • Seebeck effect;
  • electronic structure;
  • lithography

Abstract

We studied the Seebeck coefficient S of sputtered Zn0.98Al0.02O samples with free carrier concentrations varying from 1018 to 1021 cm–3. The temperature dependence of the Seebeck coefficient at low carrier concentrations exhibits typical semiconductor behavior (S < 0 and pronounced phonon drag below 80K) whereas the metallic as-grown Zn0.98Al0.02O shows a sign reversal of the Seebeck coefficient with decreasing temperature which is related to the not square-root-like density of states of this degenerately doped metallic material. Furthermore, metallic specimens were microstructured by photolithography and wet-chemical etching with a pattern based on a square grid with a unit cell consisting of a centered square-hole. The Seebeck coefficient changed systematically with decreasing size of the unit cell. The change of S is caused by a shift of the Fermi energy due to the creation of additional surface traps at the sidewalls of the micro holes (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)