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This study was meticulously conducted, delving into the epitaxial growth of nanothin β-In2Se3 films on sapphire (0001) using molecular beam epitaxy. The growth temperature was carefully set at 480 °C, and the selenium to indium flux ratio (RSe/In) was systematically varied from 1 to 100. The phase transformation from γ-In2Se3 to β-In2Se3 was precisely controlled by manipulating the RSe/In and confirmed through Raman scattering measurements and synchrotron-based grazing-incidence wide-angle X-ray scattering. The surface morphology for various RSe/In of In2Se3 was analyzed by atomic force microscopy (AFM). The lowest surface roughness is around 0.58 nm, which is achieved under the RSe/In = 60 growth condition. The nanothin β-In2Se3 film with a layer-by-layer atomic arrangement was verified by high-resolution transmission electron microscopy. According to the experimental results, the growth dynamics of In2Se3 are proposed to be step-flow growth and horizontal growth under RSe/In 45 and 60 conditions, respectively. This research underscores the control of the growth mechanism by Se/In flux and its role in facilitating the In2Se3 epitaxy for integration in the development of 2D-materials-based future electronic devices. [ABSTRACT FROM AUTHOR]

Ferroelectric HfO2 thin film has been widely explored due to its superior characteristics, such as high switching speed, scalability, and long data retention. However, it still faces challenges in achieving good stability due to the wake-up and split-up effects. In this study, the sub-cycling behavior of Hf0.5Zr0.5O2-based ferroelectric capacitors (FeCaps) with various annealing temperatures is investigated. Our results suggest that the FeCaps with higher annealing temperatures demonstrate an increased resistance to the split-up effect and exhibit less distorted hysteresis loops compared to their lower-temperature counterparts. Symmetrical sub-cycling reveals pronounced current split-up and diminished switching current peaks in the FeCaps with lower annealing temperatures, whereas those annealed at higher temperatures show minimal current split-up and enhanced performance. Asymmetrical sub-cycling shows that lower annealing temperatures cause local domain pinning, while higher temperatures result in imprint-like behavior. Synchrotron-based extended x-ray absorption fine structure and hard x-ray photoelectron spectroscopy analyses reveal the potential of nitrogen doping in HfZrOx under high-temperature annealing processes, forming the Hf–N species to mitigate the amount of charged oxygen vacancy ( V O 2 + ) in the interfacial region. This study elucidates the relationship between V O 2 + distribution and the split-up effect during sub-cycling, providing critical insights for enhancing the sub-cycling performance and stability of HfO2-based devices. [ABSTRACT FROM AUTHOR]