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HL: Halbleiterphysik
HL 3: Transporteigenschaften
HL 3.3: Vortrag
Montag, 26. März 2001, 11:00–11:15, S16
Microwave photoconductivity in porous semiconductors — •Elizaveta Konstantinova1,2, Horia Porteanu1, Victor Yu. Timoshenko1,2, Volodimyr Duzhko1, Vladimir Kytin1,2, Thomas Dittrich1, and Frederick Koch1 — 1Technische Universitaet Muenchen, Physik Department E16, D-85748 Garching, Germany — 2M. V. Lomonosov Moscow State University, Faculty of Physics, 119899 Moscow, Russia
The transient microwave photoconductivity is investigated in mesoporous silicon (meso-PS) and porous TiO2 (anatase, rutile) for different sizes of the nanoparticles and for different dielectric ambience and surface treatments. We obeserve a very fast decrease of the excess carrier concentration in meso-PS. The reduced porous TiO2 shows a longer decay time than the stoichiometric compound, probably due to trapping. The microwave photoconductivity increases if filling the pores with dielectric liquids. The transient microwave photoconductivity measurements are compared with the decay of the photocurrent in structures with lateral geometry and with time resolved photovoltage and photoluminescence. The relaxation of hot carriers plays an important role for the time dependent behavior of the microwave photoconductivity of meso-PS. The role of surface conditioning and of the dielectric ambience is discussed.