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HL: Halbleiterphysik
HL 7: Poster I
HL 7.39: Poster
Monday, March 26, 2001, 10:30–19:00, Rang S\ 3
Injection of electrons from a SnO2:F contact into porous TiO2 — •Vladimir Kytin1,2, Volodimyr Duzhko1, Frederick Koch1, Energui Lebedev3, and Thomas Dittrich1 — 1Technische Universitaet Muenchen, Physik Department E16, D-85748 Garching, Germany — 2M. V. Lomonosov Moscow State University, Faculty of Physics, 119899 Moscow, Russia — 3Ioffe Institute, Politekhnicheskaya 26, 194021 St. Petersburg, Russia
The injection of electrons from a SnO2:F contact into non-reduced TiO2 is investigated by current-voltage, impedance spectroscopy, transient current, transient photocurrent and -voltage and by spectral photocurrent and -voltage methods. The threshold for electron injection is independent of the sample thickness and the onset of injection is accompanied by strong polarization of the contact region. Electrom injection vanishes at temperatures below 240K. Transient photocurrents can be observed only for electrons and only when electron injection occurs. Strong injection currents as well as strong ultraviolet bias illumination lead to the generation of deep states in the forbidden gap of TiO2. The role of polarization and dissociation of adsorbed at the surfaces of SnO2:F and TiO2 water molecules is discussed for screening of the electric field, injection and defect generation.