Transparent electronics has attracted much attention and been widely studied for next-generation high-performance flat-panel display application in the past few years, because of its excellent electrical properties. In display application, thin film transistors (TFTs) play an important role as the basic units by controlling the pixels. Among them, oxide-based TFTs have become promising candidates and gradually replaced the conventional amorphous and polycrystalline silicon TFTs, due to high mobility, good transparency, excellent uniformity and low processing temperature. Even though n-type oxide TFTs have shown high device performance and been used in commercial display application, p-type oxide TFTs with the equal performance have been rarely reported. Hence, in this paper, recent progress and challenges in p-type oxide-based TFTs are reviewed. After a short introduction, the TFT device structure and operation are presented. Then, recent developments in p-type oxide TFTs are discussed in detail, with the emphasis on the potential p-type oxide candidates as copper oxide, tin oxide and nickel oxide. Moreover, miscellaneous applications of p-type oxide TFTs are also presented. Despite this, the performance of p-type oxide TFTs still lags behind, as compared with that of n-type counterparts. Thus, the current issues and challenges of p-type oxide TFTs are briefly discussed.

Lanthanum-doped hafnium zirconium oxide (La:HZO) has demonstrated high potential to solve the endurance challenge of hafnia-based ferroelectric memory. To date, La:HZO has been experimentally reported to exhibit ferroelectricity (FE) with lower La concentration (<1 mol. %) but anti-ferroelectricity (AFE) with higher La concentration that exceeds 1 mol. %. Despite the improved endurance with the introduction of La dopants, there still lacks an in-depth understanding to explain the mechanisms behind FE to AFE transition. In this work, we theoretically studied the origin of FE and AFE characteristics in La:HZO thin films through first-principles calculations. The polarization switching process was also analyzed based on the Landau–Ginzburg–Devonshire theory. The calculation results reveal that the dominant phase in La:HZO changes from non-FE monoclinic to FE orthorhombic to AFE tetragonal phase with increasing the concentration of La dopants, which results in FE-AFE transition. During the process, the presence of oxygen vacancies also facilitates the formation of the tetragonal phase, which highlights the significant role of oxygen vacancies in phase stabilization. Our findings explain the physical origin of the narrow doping window in La:HZO and provide a theoretical basis for optimizing HZO-based ferroelectric devices by regulating the concentration of dopants and oxygen vacancies within the film.

In this work, we investigate the ferroelectricity of stacked zirconium oxide and hafnium oxide (stacked HfZrO) with different thickness ratios under metal gate stress and simultaneously evaluate the electrical reliability of stacked ferroelectric films. Based on experimental results, we find that the stacked HfZrO films not only exhibited excellent ferroelectricity but also demonstrated a high performance on reliability. The optimized condition of the 45% Zr proportion exhibited a robust ferroelectric polarization value of 32.57 μC/cm², and a polarization current with a peak value of 159.98 μA. Besides this, the ferroelectric stacked HfZrO also demonstrated good reliability with a ten-year lifetime under >−2 V constant voltage stress. Therefore, the appropriate modulation of zirconium proportion in stacked HfZrO showed great promise for integrating in high-performance ferroelectric memory.

From their experimental results, Hsiao‐Hsuan Hsu and co‐workers (article number 2000258) found that the enhanced ferroelectric polarization effect within HfAlO under annealing can be ascribed to the generation of a nonlinear thermal stress distribution between the TaN gate and HfAlO film in a ferroelectric capacitor. To further improve the device performance, the authors introduce a remote nitrogen‐plasma treatment on the ferroelectric HfAlO film. This treatment not only reduces the leakage current, but also enhances the thermal stability during the period of ferroelectric phase transition induced by gate thermal stress. The demonstrated p‐type SnO thin‐film transistor with the integration of ferroelectric HfAlO capacitor achieved an almost 43% improvement on threshold voltage shift under a low operating voltage of 3 V, which shows the potential for display and memory applications.