Paramasivam Balasubramanian

In this letter, the cause of the poor uniformity in indium tungsten oxide (IWO) thin-film transistors (TFTs) is investigated. The significant fluctuation in tungsten (W) content, which results from the non-uniformity of the IWO target, is responsible. To solve this problem, RF magnetron co-sputtering of In ₂ O ₃ and WO ₃ targets is adopted to eliminate the variation of W content, thereby achieving high-uniformity IWO TFTs with enhanced performance. This co-sputtering methodology could shed light on the pathways for mitigating the device uniformity challenges encountered in mass production settings, thus leading to substantial cost reductions.

The device performance of indium zinc oxide (IZO) thin-film transistors (TFTs) is optimized through process optimizations. By jointly adjusting the annealing condition, the channel thickness and the sputtering atmosphere, the roughness and oxygen vacancies (Vos) are precisely regulated. The optimized IZO TFTs can achieve the highest field effect mobility of ~71.8 cm2/Vs with a threshold voltage of ~ –0.6 V. Reliability of IZO TFTs under positive/negative bias stress is also examined. The interface quality and the Vos are two key factors influencing the device performance and reliability, confirmed by X-ray photoelectron spectroscopy and atomic force microscopy analysis.