Homm, G.G.HommTeubert, J.J.TeubertHenning, T.T.HenningKlar, P.J.P.J.KlarSzyszka, B.B.Szyszka2022-03-042022-03-042010https://publica.fraunhofer.de/handle/publica/22386410.1002/pssc.2009831692-s2.0-77955464445We studied the Seebeck coefficient S of sputtered Zn0.98Al 0.02O samples with free carrier concentrations varying from 10 18 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.en667journal article