Regensburg 2013 – scientific programme

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DS: Fachverband Dünne Schichten

DS 28: Layer Properties: Electrical, Optical, and Mechanical Properties

DS 28.4: Talk

Thursday, March 14, 2013, 10:15–10:30, H8

CVD-Like Growth Mechanism and 3D Nucleation in ZnO-TFTs Deposited by Pulsed Spray Pyrolysis — •Marlis Ortel and Veit Wagner — Research Center for Functional Materials and Nanomolecular Science, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany

Zinc oxide is a promising material for large area electronics due to high mobility and large area compatible deposition techniques. Proper film formation is crucial to obtain high quality layers. We investigate the growth and nucleation of zinc oxide thin films deposited by pulsed spray pyrolysis from aqueous zinc-precursor solution is investigated. The Leidenfrost effect was found to be a crucial mechanism during film growth since the Leidenfrost point has to be exceeded to form high quality layers. Furthermore, it is concluded that 3D nucleation of ZnO nano-crystals takes place out of the gaseous phase by a CVD-like process on ITO as well as on SiO2 substrates. Surface crystal orientation and roughness of the zinc oxide layer are found to be substrate dependent. These findings were utilized to optimize the deposition of the active layer in a zinc oxide thin film transistor (TFT) and investigate its semiconducting properties as degree of quality of the functional layer. Under optimized conditions the mobility was found to exceed 12cm2V-1s-1, the on-set was at 1V and the on-off current ratio was found to be higher than 108.