Berlin 2012 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 43: Poster Session: Quantum Dots and Wires - Preparation and Characterization / Devices (incl. Laser) / Ultrafast Phenomena
HL 43.18: Poster
Tuesday, March 27, 2012, 09:30–12:30, Poster D
All-oxide junction field-effect transistors — •Friedrich-Leonhard Schein, Holger von Wenckstern, Heiko Frenzel, and Marius Grundmann — Institut für Experimentelle Physik II, Fakultät für Physik und Geowissenschaften, Universität Leipzig, Germany
We report on the first ZnO-based junction field-effect transistors (JFETs) using an all-oxide p-n-junction as top-gate contact. The oxide materials were grown by pulsed-laser deposition on an a-plane sapphire substrate. A ZnO channel layer was deposited at 680 ∘C followed by room temperature deposited p-type ZnCo2O4. Sputtered Au contacts serve as Ohmic source and drain electrodes as well as current spreading layer for the gate electrode. Standard photolithography and lift-off was used for device processing. The p-type conductivity of ZnCo2O4 thin films [1, 2], which are X-ray amorphous if grown at room temperature, was confirmed by Seebeck effect measurements. An average transmittance of TVIS = 54 % was determined for a 40 nm thin film of this material.
The normally-on JFETs exhibit a channel mobility of µch = 8.4 cm2/Vs, a subthreshold slope S = 91 mV/decade and a current on/off-ratio larger than 107. These properties are similar to that of the best oxide-based FETs, typically having µch = 5−15 cm2/Vs, S < 100 mV/decade and Ion/off>107 [3].
[1] M. Dekkers et al., Appl. Phys. Lett. 90, 021903 (2007).
[2] S. Kim et al., J. Appl. Phys. 107, 103538 (2010).
[3] M. Grundmann et al., Phys. Status Solidi A 207, 1437 (2010).