Preparation of ZnO thin films by MO-CVD method using bis(acetylacetonato) zinc(II) anhydrate fiber

The MO-CVD method as a deposition process corresponding to the mass production of the high-quality ZnO film that can be used as an active layer in the thin film transistor is paid to attention. Bis(acetylacetonato) zinc(II) (Zn(acac)2) which has chemical stability and low toxicity is promising as the inexpensive raw material for CVD. The problem includes (1) pollution with water in process by character to easily take water of crystallization, and (2) the supply of the gas-phase raw material by sublimation should be not able to be controlled easily because it is a fine particle. In this study, Zn(acac)2 anhydrate fiber was prepared from Zn(acac)2 monohydrate powder by the sublimation process. Melting point of this fiber was almost same (∼134 °C) as the monohydrate powder in N2 atmosphere. ZnO film was deposited on r-face sapphire substrate by MO-CVD process using Zn(acac)2 anhydrate fiber, successfully. RMS of the film flatness was 0.48 nm. This film had resistivity of 4.6 × 10–1 Ω·cm, carrier electron density of 9.1 × 1017 cm–3 and Hall mobility of 15 cm2·V–1·s–1. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)