Preparation And Stress Regulation Of Flexible Transparent HfO₂-Based Ferroelectric Thin Films

Flexible electronics has long been considered the next technology hotspot for advanced manufacturing and new product development,attracting significant interest from academia,business,and government in recent decades.Memory is also essential in the growing flexible electronic equipment as a key component of data processing systems.Because of its unique information storage mechanism,ferroelectric memory,as an emerging nonvolatile memory,is expected to break past the development bottleneck of traditional storage structures,stimulating storage technology development.Additionally,in terms of compatibility with the CMOS process and high-density storage,the new type HfO₂-based ferroelectric thin films outperform traditional ferroelectric thin films.It is expected to realize the development of flexible transparent ferroelectric memory and be employed in biomedicine,wearable devices,and other industries based on the favourable light transmittance of HfO₂-based ferroelectric film and the existing preparation technology of flexible ferroelectric film.However,there are still few reports on flexible transparent HfO₂-based ferroelectric thin films.Therefore,this work will study the preparation and properties of flexible transparent HfO₂-based ferroelectric thin films,and explore the effect of in-situ stress on ferroelectricity.The following three aspects have been completed:（1）Ce-doped HfO₂ ferroelectric thin films were prepared on artificial mica substrate with indium tin oxide（ITO）as transparent bottom electrode by chemical solution deposition（CSD）.The transparent flexible film has satisfactory light transmittance in the visible wavelength region,with an average light transmittance of more than 80%and excellent surface flatness.GIXRD and TEM were used to determine the presence of an orthorhombic ferroelectric phase（Pca2₁）in multiphase coexisting flexible transparent Ce:HfO₂ ferroelectric thin films.Furthermore,the film exhibits good macroscopic electrical properties,with a 2P_r of around 33.3μC/cm² and a polarization value of nearly 90%even when the polarization reversal times of the film approach 10⁸ times.The retention performance of the film is also good,and its remnant polarization value does not decay seriously after 10⁴ seconds.（2）To evaluate the reliability of transparent ferroelectric memory in unique application situations,the properties of a flexible transparent Ce:HfO₂ ferroelectric thin film are tested under additional conditions such as stress and high temperature.It is discovered that stress loading has no significant effect on the film’s ferroelectric and dielectric properties,but has a significant detrimental impact on its fatigue properties.Moreover,following multiple bending,the macroscopic electrical properties of the films,as well as the domain inversion properties at high temperatures and bending,can remain stable.（3）In-situ stress of various types and sizes was used in the fabrication of flexible transparent Ce:HfO₂ ferroelectric films,and the influence of stress on the films’characteristics was investigated.Specifically,an experimental scheme that can realize the preparation of flexible transparent HfO₂-based ferroelectric thin films under in-situ stress loading is designed,and the design and processing of the die required for film stress loading are completed.Through the tests of flexible ferroelectric films prepared based on in-situ stress loading,the results show that the in-plane stress in a certain range will improve the ferroelectricity.