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Recently, hafnia-based ferroelectrics are currently being investigated as next-generation memory devices due to their excellent CMOS process compatibility and functionality. However, some of the ferroelectric devices commonly exhibit an imprint effect due to charged defects around the interfacial layer, which has negative impacts on the ferroelectric memory devices. However, it can be applied to various applications as long as the imprint field is carefully adjusted. In this work, we introduced a strategy to control the imprint field in bilayer capacitors by utilizing tantalum oxide (TaO) interfacial layers and various Zr contents in Hf0.83Zr0.17O2 (HZO) films. The TaO layer (1 nm) was inserted into the bilayer capacitors to alter the imprint field's (positive or negative) direction. Whereas to control the imprint fields, we adjusted the Zr doping content (17%–83%) in the ferroelectric HZO films (8 nm). As the Zr content increased, reduced imprint fields were observed in those bilayer capacitors. In addition, it was found that a high imprint field (+2.43 MV/cm) was observed in Hf-rich films (Hf0.83Zr0.17O2) due to the higher amount of oxygen vacancies. In addition, we examined those oxygen vacancies through x-ray photoelectron spectroscopy depth profile analysis by considering sub-oxide fractions in the tantalum, which further confirms the root cause of the imprint field variations in the bilayer capacitors. Our study will contribute to a deeper understanding of imprinted hafnia-based ferroelectrics and will provide an insight into devices that utilize the imprint effect.

The passivation layers that should be formed on flexible electronics devices require high mechanical stability. Therefore, organic passivation has been used to enhance the electrical characteristics of various devices such as thin-film transistors (TFTs), organic light emitting diodes, and capacitors under mechanical stress. However, the conventional deposition of an organic film based on spin coating results in excessive thickness and the potential for chemical damage due to by-products such as organic solvents throughout the process. Here, we present the effects of a poly(1,3,5-trimethyl-1,3,5-trivinyl cyclotrisiloxane) organic passivation layer deposited by initiative chemical vapor deposition (iCVD) on the electrical and mechanical stabilities of oxide TFTs subjected to 30 000 repetitive tensile bending cycles. The highly ultrathin (50 nm) and excellent roughness (Rq = 0.33 nm) of the pV3D3 film assisted in preserving the mechanical stability of the device under external mechanical stress, and degradation of the electrical properties was suppressed compared with a device using SiO2 passivation. The mechanical properties of the type of passivation layer, including its Young’s modulus, affected the degradation of the electrical properties and reliability characteristics under repetitive bending. Finite-element structural simulations indicated a 15% reduction in equivalent stress applied to each layer of the device when pV3D3 (versus SiO2 passivation) was used. The iCVD-deposited pV3D3 film used in this study is a powerful candidate to act as the passivation layer of flexible electronics by strengthening the electrical stability of a device under external mechanical stress.

A relatively low-temperature process is required to fabricate amorphous oxide thin film transistor (TFT) display backplanes for flexible electronics. However, in order to ensure the outstanding electrical property of TFT, a typical post-annealing process should be performed at 300 °C or above. This is not compatible with flexible substrates in the process. In our work, we applied microwave annealing (MWA) at a low-temperature (150 °C) to the oxide TFT and verified its feasibility through the evaluation of various electrical properties. Even an a-IGZO TFT by MWA at such a low-temperature shows high mobility (29.0 cm2/V s) by DC ID-VG measurement, which is 4 ∼ 5 times higher than other counterparts, indicating that the MWA process is very effective to minimize the defects in an oxide semiconductor channel. To further investigate the intrinsic mobility of TFT with negligible charge trapping, we carried out fast and pulse ID-VG measurement methods. The intrinsic mobility extracted from this measurement is found to be 35.3 cm2/V s, 21.7% higher than that of DC ID-VG. We are expecting that the low-temperature MWA process would be widely used for the process of oxide TFT in a flexible platform.