The transfer characteristics of amorphous indium gallium zinc oxide thin film transistor (a-IGZO TFT) showed the distortion in the subthreshold region after gate bias stress, in addition to the parallel shift of threshold voltage. The capacitancevoltage (C-V) curve was also deformed from its initial shape after the gate bias stress. This study analyzes both the C-V and transfer curves plotted on the same gate voltage axis in order to investigate the mechanism driving the distortion in the transfer curve. It is deduced that an additional interfacial trap states at the bottom interface of a-IGZO are produced during gate bias stress, thereby they exhibit the back channel effect, which explains the origin of the distortion in the transfer curve and the deformation of C-V curve.
For the last decades, a research hotspot for the halide perovskites (HPs) is now showing great progress in terms of improving efficiency for numerous photovoltaic devices (PVDs). However, it still faces challenges in the case of long-term stability in the air atmosphere. Defect-free high-quality HP single crystals show their promising properties for the remarkable development of highly efficient and stable PVDs. Here, we summarize the growth processing routes for the stable HP single crystals as well as briefly discuss the pros and cons of those well-established synthesis routes. Furthermore, we briefly include the comparison note between the HP single crystals and polycrystalline perovskite films regarding their device applications. Based on the future progress, the review concludes subjective perspectives and current challenges for the development of HPs high-quality PVDs.
This study investigated the structural, dielectric, ferroelectric, and strain properties of (0.98-x)Bi1/2Na1/2TiO30.02BiFeO3-xSrTiO3 (BNT-BF-100xST, x=0.20, 0.22, 0.24, 0.26, and 0.28). All samples were successfully synthesized using the conventional solid-state reaction method and sintered at 1,175°C for 2 h. The average grain size of the BNT-BF-100x ceramics decreased with increasing ST content. Furthermore, we observed that the ferroelectricrelaxor transition temperature (TF-R) decreased with increasing ST content, which eventually vanished in the BNT-BF-24ST ceramics. The results indicated that a ferroelectric to relaxor phase transition could be induced by ST modification. Consequently, a large electromechanical strain of 633 pm/V at 4 kV/mm was observed for the BNT-BF-26ST ceramics. These results imply that our materials have the competitive advantage of larger strain under lower operating field conditions compared with other BNT-based lead-free piezoelectric ceramics. We expect that BNT-BF-ST lead-free piezoelectric ceramics are promising candidates as a novel ternary BNT-based system and can find potential applications
High reliability thin film transistors are important factors for next-generation displays. The reliability of transparent a-IGZO semiconductors is being actively studied for display applications. A plasma treatment can fill the oxygen vacancies in the channel layer and the channel layer/insulating layer interface so that the device can work stably under a bias voltage. This paper studies the effect of plasma treatment on the performance of a-IGZO TFT devices. The influence of different plasma gases on the electrical parameters of device and its working reliability are reviewed. The article mentions argon, fluorine, hydrogen and several ways of processing in the atmosphere. Among these methods, F (fluorine) plasma treatment can maximize equipment reliability. It is expected that the presented results will form a basis for further research to improve the reliability of a-IGZO TFT.
