Sputter coated nanocrystalline ZnO for fabrication of thin film transistors

Fabrication of zinc oxide based thin-film transistors (ZnO-TFT), by RF magnetron sputtering at room temperature has been realized on thermally oxidized silicon wafer followed by the metal evaporation and lift-off process. The configuration of the TFT was bottom gate with the gold contacts on P-doped silicon. The device was observed to be a “normally on” device. Electrical characteristics, mainly, channel mobility, on/off ratio, and threshold voltage were extracted from the electrical characterization of TFT. The ZnO-TFT was found to operate with a threshold voltage of 12.075 V, channel mobility of 110.44 cm²/Vs, and an on/off ratio of approximately 10⁵. Thickness of the ZnO film was confirmed by the UV spectrometer. No photo effect was observed, making it an ideal material for flat-panel displays. X-ray diffraction was performed to find out the orientation of the ZnO layer on the substrates. Preferred orientation was in the 002 plane. The high mobilities, ease of fabrication and cost-effectiveness make the ZnO-TFT a very desirable electronic device for futuristic flexible electronics.