Quasi-Dual-Channel Oxide Transistors With Enhanced Stability and Performance

Metal oxide thin-film transistors (MO TFTs) have emerged as promising candidates for next-generation displays owing to their high electron mobility and excellent optical transparency. However, device stability depends heavily on the oxygen content: an excess results in poor positive bias stress (PBS) stability, whereas a deficiency leads to degraded negative bias stress (NBS) stability. This sensitivity makes precise control of oxygen content critical, but significantly narrows the processing window. This study introduces a quasi-dual channel strategy to overcome the issue. The proposed TFTs are composed of a channel layer of oxygen-rich tantalum-doped tin oxide (TTO) and an insulator layer of HfO_x with an oxygen-deficient surface. Compared to conventional TTO/SiO₂ TFTs, the device exhibits significantly reduced threshold voltage shifts under PBS and NBS, decreasing from 8.82 and -1.07 V to 0.09 and -0.11 V, respectively. In addition, a 4.4-fold enhancement in mobility was achieved. This quasi-dual channel design holds promise for general application in oxide TFTs, enabling improved process tolerance.