AVS 53rd International Symposium
    Electronic Materials and Processing Thursday Sessions
       Session EM-ThP

Paper EM-ThP7
Reliability of Gate Dielectrics for ZnO Thin-Film Transistors Operating at Low Voltages

Thursday, November 16, 2006, 5:30 pm, Room 3rd Floor Lobby

Session: Electronic Materials and Processing Poster Session
Presenter: M.S. Oh, Yonsei University, Korea
Authors: M.S. Oh, Yonsei University, Korea
K.M. Lee, Yonsei University, Korea
K.H. Choi, Yonsei University, Korea
S. Im, Yonsei University, Korea
Correspondent: Click to Email
ZnO-based thin-film transistors (TFTs) have attracted much attention from researchers and engineers because of their novel potentials: the realization of transparent TFTs, replacing amorphous Si-TFTs, and being a component of effective ultraviolet (UV) detecting devices. PECVD(Plasma Enhanced Chemical Vapor Deposition) SiN@sub x@ has been used as a gate dielectric in the fabrication of amorphous silicon (a-Si:H) TFT arrays for large area liquid crystal displays(LCDs). Since PECVD is a low-temperature process and the SiN@sub x@ layer is a transparent materials, SiN@sub x@ is one of the powerful candidates for the dielectric layer in transparent electronics applications using ZnO-based TFTs. Additionally the dielectric constant of SiN@sub x@ is quite high (~7), so that we may drive the ZnO-TFTs at low voltage(~5V) if the dielectric is as thin as 200 nm (resultant capacitance ~31 nF/cm@super 2@). We have fabricated the ZnO-based TFTs with 200 nm-thick SiN@sub x@ dielectric layers which were deposited by PECVD. The undoped ZnO was used for a channel layer and was deposited by rf sputtering at room temperature. For the source/drain electrodes, we have used the Al and the substrate was an ITO glass. The field mobility of our ZnO-TFT was ~0.7cm@super 2@/Vs while the turn-on voltage was less than ~5V. However, our ZnO-TFT also showed inferior on/off current ratio of less than 10@super 3@ and unreliable gating with a large gate voltage hysteresis, of which the origin is not clear but probably related to deposition-induced-hydrogen in SiN@sub x@. In the present work, the reliability of SiN@sub x@ dielectric for ZnO-TFT will be discussed in detail and another results from adopting different gate dielectric such as rf sputter-deposited AlO@sub x@ will also be presented.