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HL: Fachverband Halbleiterphysik
HL 39: ZnO and Relatives II
HL 39.2: Vortrag
Dienstag, 27. März 2012, 11:45–12:00, EW 202
Passivation of tungsten trioxide gated MISFETs based on ZnO channel material — •Anna Reinhardt, Michael Lorenz, Holger von Wenckstern, and Marius Grundmann — Universität Leipzig, Institut für Experimentelle Physik II, Semiconductor Physics Group
Recently, tungsten trioxide was reported to be an advantageous high-k gate oxide for transparent MISFETs with large on/off current ratios and low gate-voltage sweeps due to a high dielectric constant (єr≈ 70)[1]. However, a slight hysteresis limiting the device switching speed occurs in the transfer characteristic.
The passivation of TFTs with lithographically processed SU-8 resist is very promising, providing a non-vacuum and low temperature process (max. 90 ∘C) compared to other deposition methods for passivation layers such as sputtering. We present our results on passivated tungsten oxide gated MISFETs deposited at room temperature on ZnO channel using pulsed-laser deposition. The electrical properties including on/off ratio, field-effect mobility and transfer characteristic are investigated by current-voltage measurements. In order to investigate the origin of the hysteresis and to study the distribution and density of defects quasi-static capacitance-voltage measurements as well as capacitance-voltage spectroscopy using different probing voltage frequencies were performed. Furthermore, time and temperature stability is compared to unpassivated devices.
[1] M. Lorenz et al., Adv. Mater., doi: 10.1002/adma.201103087