ABSTRACT Ferroelectric topological domain textures hold promise as key building blocks for next‐generation nanoelectronic devices. However, the scalable fabrication and deterministic control of ordered domain states remain challenging. In this work, we achieve the controlled creation of ordered center‐type topological domain configurations in periodically wrinkle‐patterned Pb(Zr 0.2 ,Ti 0.8 )O 3 (PZT) thin films and demonstrate their reversible manipulation using mechanical force and electric field, respectively. We further identify high‐conduction channels confined to the topological cores of these center‐type domain states. By applying a localized mechanical stress via an atomic force microscope (AFM) tip, a reversible transformation from an initial center‐convergent to a center‐divergent topological state is realized. This domain state transition is attributed to the flexoelectric effect, which modulates both the local depolarization field and the distribution of screening charges. Moreover, the center‐divergent state can be switched back to the convergent state by applying an electric field. These findings establish a pathway toward multifield control of polar topologies, offering a promising route for the development of emerging functional devices based on topological domain textures.
ABSTRACT HfO 2 /ZrO 2 superlattice (SL) materials hold significant promise for high‐performance electronics, primarily due to their low‐power consumption and seamless compatibility with complementary metal‐oxide‐semiconductor (CMOS) technologies. However, the stringent requirements for dimensional scaling and high‐density integration in advanced memory technologies have made it urgent to overcome the challenge of thickness scaling while maintaining high permittivity. In this work, we experimentally demonstrate thickness‐scaled HfO 2 /ZrO 2 SL films with thicknesses of 7.5 and 5 nm, which exhibit high permittivity values ( κ ) exceeding 75 and 68, respectively. These results were achieved by leveraging morphotropic phase boundary (MPB) engineering through optimized HfO 2 /ZrO 2 sublayer stacking in conjunction with process optimization, including the tuning of HfO 2 /ZrO 2 superlattice periodicity and annealing temperatures. Owing to the enhanced κ values and reduced film thickness, these SL films maintain low leakage current and robust endurance up to 10 11 cycles. Moreover, systematic electrical characterization reveals outstanding thermal stability across a broad temperature range from 4 to 425 K, alongside excellent device reliability. This work highlights the scaling potential of high‐ κ SL materials, providing a viable pathway for the next generation of low‐power logic and embedded memory applications.
ABSTRACT Hydrogen‐bonded organic frameworks (HOFs) combine crystallinity with dynamic reversibility, yet their weak interlayer interactions pose a fundamental challenge: how to suppress nonradiative decay without sacrificing structural adaptability. This review critically surveys recent progress in luminescent HOFs across three interconnected pillars: fluorescence enhancement through linker rigidification, AIE core integration, and heterostructure engineering; ultralong room‐temperature phosphorescence via heavy atom effects, framework confinement, and triplet to singlet Förster resonance energy transfer; and stimuli‐responsive emission switching upon physical stimuli, such as light, electricity, force, and temperature, as well as chemical triggers including ions, gases, and pH. Distinct from previous accounts, we analyze structure‐property relationships rather than cataloging examples, provide quantitative comparisons through summary tables, and include a dedicated section on key photophysical mechanisms to aid nonspecialist readers. We further identify persistent bottlenecks, including aqueous stability, scalable synthesis, and device integration, and outline a roadmap toward next‐generation HOFs for chemical sensing, bioimaging, and optoelectronics.
ABSTRACT The continuous scaling of complementary metal–oxide–semiconductor technology has created an urgent demand for emerging materials that go beyond silicon. Two‐dimensional (2D) oxides have emerged as promising candidates for post‐Moore information devices, attributed to their outstanding structural stability, inherent compatibility with silicon‐based technology, and diverse functionalities encompassing semiconducting behavior, high‐ κ dielectric response, ferroelectricity, and magnetism. The two‐dimensionalization of nonlayered bulk oxides breaks the inherent limitation of strong three‐dimensional bonding, thereby greatly extending the material family of 2D oxides; this holds great scientific significance for exploring emergent physical properties and device applications. This review systematically presents the classification, synthesis strategies, fundamental physical properties, and device applications of both 2D layered and nonlayered oxides. We highlight key progress in transistors, gate dielectrics, optoelectronic components, as well as 2D ferroelectric and magnetic systems. Finally, we discuss the current challenges pertaining to scalable fabrication, interface engineering, and complementary integration, and offer perspectives on future pathways toward industrial translation and practical electronic applications.
ABSTRACT Beta‐phase gallium oxide ( β ‐Ga 2 O 3 ) is a promising ultra‐wide bandgap semiconductor for high‐power electronics, where the optimal selection of Schottky electrodes enables the achievement of elevated Schottky barrier heights and markedly enhanced device performance. This study investigates the impact of Ni diffusion on the leakage current in (100) β ‐Ga 2 O 3 Schottky barrier diodes (SBDs). Devices were fabricated using electron beam evaporation for Ni and Au Schottky contacts on unintentionally doped single crystals, with Ti/Au ohmic back contacts. Electrical measurements showed Ni‐SBDs exhibit higher reverse leakage current (−0.65 mA/cm 2 at −50 V) and lower Schottky barrier height (1.03 eV) compared to Au‐SBDs (−3.64 nA/cm 2 at −50 V) and (1.41 eV). Cross‐sectional corrected scanning transmission electron microscopy (CS‐STEM) and electron energy loss spectroscopy (EELS) revealed Ni diffusion at the interface of metal and β ‐Ga 2 O 3 , introducing oxygen vacancies that facilitate trap‐assisted tunneling and reduce barrier integrity. Emission microscopy (EMMI) localized leakage sites, which after KOH etching, corresponded to elongated etch pits. Geometric phase analysis (GPA) confirmed continuous strain beneath these pits. Magnetron‐sputtered Ni electrodes (Ni‐MS) amplified diffusion and defects, with voids as primary channels due to enhanced stress concentration. These results elucidate that Ni diffusion‐induced stress damage is the dominant mechanism for leakage under reverse bias, offering guidance for electrode optimization in β ‐Ga 2 O 3 power devices.
