Reduction of the interfacial trap density of indium-oxide thin film transistors by incorporation of hafnium and annealing process

The stable operation of transistors under a positive bias stress (PBS) is achieved using Hf incorporated into InOx-based thin films processed at relatively low temperatures (150 to 250 degrees C). The mobilities of the Hf-InOx thin-film transistors (TFTs) are higher than 8 cm(2)/Vs. The TFTs not only have negligible degradation in the mobility and a small shift in the threshold voltage under PBS for 60 h, but they are also thermally stable at 85 degrees C in air, without the need for a passivation layer. The Hf-InOx TFT can be stable even annealed at 150 degrees C for positive bias temperature stability (PBTS). A higher stability is achieved by annealing the TFTs at 250 degrees C, originating from a reduction in the trap density at the Hf-InOx/gate insulator interface. The knowledge obtained here will aid in the realization of stable TFTs processed at low temperatures. (C) 2015 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.