Mobility enhancement in ZnO-based TFTs by H treatment

ZnO-based thin-film transistors (TFTs) have been fabricated by depositing ZnO (radio-frequency sputtering) on SiO2/p-Si substrates at various temperatures ranging from room temperature to 300 degrees C. When rapid thermal annealing in a forming gas ambient was used for H treatment on ZnO, the TFTs prepared at 200 degrees C exhibited a high field-effect mobility of similar to 1.93 cm(2)/V s but a low on/off current ratio of similar to 10(2) while those fabricated at room temperature showed a low mobility (similar to 0.2 cm(2)/V s) but a high on/off ratio (similar to 10(6)). The TFT fabricated at 300 degrees C was the most highly conductive among all the TFTs studied but did not show current saturation. We conclude that H treatment on the ZnO channel at a high temperature leads to a high mobility but to a low on/off current ratio. (C) 2004 The Electrochemical Society.