High-performance Schottky diodes based on palladium blocking contacts were fabricated upon depositing indium-gallium-zinc oxide (IGZO) with high oxygen content. We find that an oxygen treatment of the palladium contact is needed to achieve low off currents in the Schottky diode, and rationalize this by relating an increased oxygen content at the Pd/IGZO interface to a lower interfacial trap density. Optimized IGZO films were obtained with a record high ratio of free charge carrier density to subgap traps. The rectification ratios of diodes with such films are higher than 107 with current densities exceeding 103 A/cm2 at low forward bias of 2 V.

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In this study, the authors report on high‐quality amorphous indium–gallium–zinc oxide thin‐film transistors (TFTs) based on a single‐source dual‐layer concept processed at temperatures down to 150°C. The dual‐layer concept allows the precise control of local charge carrier densities by varying the O2/Ar gas ratio during sputtering for the bottom and top layers. Therefore, extensive annealing steps after the deposition can be avoided. In addition, the dual‐layer concept is more robust against variation of the oxygen flow in the deposition chamber. The charge carrier density in the TFT channel is namely adjusted by varying the thickness of the two layers whereby the oxygen concentration during deposition is switched only between no oxygen for the bottom layer and very high concentration for the top layer. The dual‐layer TFTs are more stable under bias conditions in comparison with single‐layer TFTs processed at low temperatures. Finally, the applicability of this dual‐layer concept in logic circuitry such as 19‐stage ring oscillators and a TFT backplane on polyethylene naphthalate foil containing a quarter video graphics array active‐matrix organic light‐emitting diode display demonstrator is proven.

In this work a technology to fabricate low-voltage amorphous gallium-indium-zinc oxide thin film transistors ͑TFTs͒ based integrated circuits on 25 m foils is presented. High performance TFTs were fabricated at low processing temperatures ͑Ͻ150°C͒ with field effect mobility around 17 cm 2 / V s. The technology is demonstrated with circuit building blocks relevant for radio frequency identification applications such as high-frequency functional code generators and efficient rectifiers. The integration level is about 300 transistors.