Berlin 2015 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

HL: Fachverband Halbleiterphysik

HL 20: Poster IA (Ultrafast phenomena; Optical properties; Transport; Theory)

HL 20.17: Poster

Montag, 16. März 2015, 15:00–20:00, Poster B

Activated transport in nanoporous titanium dioxide under hydrogen exposure — •Sonja Allani¹, Thomas Heinzel¹, Mihai Cerchez¹, and Klaus Schierbaum² — ¹Solid State Physics Laboratory (IPkM), Heinrich-Heine-Universität Düsseldorf, 40204 Düsseldorf, Germany — ²Materials Science Laboratory (IPkM), Heinrich-Heine-Universität Düsseldorf, 40204 Düsseldorf, Germany

Nanoporous titanium dioxide is reduced to TiO_2−δ by thermal annealing. The oxygen vacancies act as donors and increase the conductivity. This material has been used for hydrogen sensing in the ppm range, [1] but the hydrogen-induced transport mechanism is not fully understood. Here, we present temperature dependent transport experiments of this material in the presence of atomic hydrogen. We observe a strongly decreasing conductivity as the temperature is decreased from 300 K to 40 K. The temperature dependence is consistent with both activated transport and variable range hopping within experimental uncertainties. Moreover, the current-voltage characteristics are nonlinear, incidating that reduced titanium dioxide does not become metallic under hydrogen exposure that is typical for sensing applications.
[1] M. Cerchez, H. Langer, M. El Achhab, T. Heinzel, D. Ostermann, H. Lüder, and J. Degenhardt, Appl. Phys. Lett. 103, 033522 (2013).