Dresden 2006 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 21: Transport properties I

HL 21.2: Vortrag

Dienstag, 28. März 2006, 16:45–17:00, BEY 118

Characterization of Ti / TiO_2 / Pt - Schottky diodes — •Philipp Zabel¹, Sven Bönisch¹, Germà García-Belmonte², Juan Bisquert², and Thomas Dittrich¹ — ¹Hahn-Meitner-Institut, Glienicker Str. 100, 14109 Berlin, Germany — ²Departament de Ciències Experimentals, Universitat Jaume I, E-12080 Castelló, Spain

UV photodiodes (sglux tw30sx, TiO_2 made by sol-gel processing) were used as a model system to study Ti / TiO_2 / Pt - Schottky diodes by temperature dependent current-voltage, impedance spectroscopy and transient photocurrent measurements. The equivalent circuit has been taken into account for the analysis. The Schottky barrier is about 1.3 eV which is equal to the work function difference between Ti and Pt. At lower potentials, the current is limited by the barrier while at higher potentials, control by space charge limited currents sets on. The temperature dependent dielectric constant of the TiO_2 layer was obtained. Photocurrent transients were excited with short UV laser pulses. The current at 1 µs and the integral of the photocurrent transients depend linearly on the laser intensity until an electron density of about 10^{12} cm^{-2} is reached in the TiO_2 layer (thickness 160 nm). At higher intensities, the photocurrent goes to saturation due to recombination. The electron drift mobility depends only weakly on the illumination intensity and temperature.