Berlin 2012 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 92: Poster Session: II-VI Semiconductors & ZnO and related Materials
HL 92.16: Poster
Donnerstag, 29. März 2012, 16:00–19:00, Poster D
Tungsten trioxide as high-κ gate dielectric for highly transparent and temperature-stable zinc-oxide-based thin-film transistors — •Michael Lorenz, Holger von Wenckstern, and Marius Grundmann — Universität Leipzig, Fakultät für Physik und Geowissenschaften, Institut für Experimentelle Physik II, Linnéstr. 5, 04103 Leipzig
We demonstrate metal-insulator-semiconductor field-effect transistors with high-κ, room-temperature deposited, highly transparent tungsten trioxide (WO3) as gate dielectric [1]. The channel material consists of a zinc oxide (ZnO) thin-film. The transmittance and resistivity of WO3 films was tuned in order to obtain a highly transparent and insulating WO3 dielectric. The devices were processed by standard photolithography using lift-off technique. On top of the WO3 dielectric a highly transparent and conductive oxide consisting of ZnO: Al 3% wt. was deposited. The gate structure of the devices exhibits an average transmittance in the visible spectral range of 86%. The on/off-current ratio is larger than 108 with off- and gate leakage-currents below 3× 10−8 A/cm2. Due to the high relative permittivity of εr ≈ 70, a gate voltage sweep of only 2 V is necessary to turn the transistor on and off with a minimum subthreshold swing of 80 mV/decade. The channel mobility of the transistors equals the Hall-effect mobility with a value of 5 cm2/Vs. It is furthermore shown, that the devices are stable up to operating temperatures of at least 150∘C.
[1] M. Lorenz, H. von Wenckstern, M. Grundman, Adv. Mater. 2011, doi: 10.1002/adma.201103087