We demonstrate a novel method using electric field cycling to induce a phase transition in Hf _x Zr _1−x O ₂ to reach the morphotropic phase boundary of tetragonal and orthorhombic phase. Conventional methods used to induce the phase transition, such as high temperature annealing, cannot be used with the DRAM cell capacitor fabrication process because it associates with grain enlargement, increased leakage current, and a narrow process margin due to the metastability of the morphotropic phase boundary. To achieve an morphotropic phase boundary in Hf _x Zr _1−x O ₂ without high temperature annealing and without increasing leakage current, we propose a two-step process, using low temperature annealing to form the tetragonal phase and electric field cycling to achieve the morphotropic phase boundary of tetragonal and orthorhombic phase in Hf _x Zr _1−x O ₂ film. This approach enabled us to achieve both low voltage with high dielectric k value, and low leakage current, meeting the requirements for the next-generation DRAM cell capacitor dielectric materials.

Ferroelectric Hf_xZr_yO_z (HZO) with an average polarization switching window of 32 µC/cm² was demonstrated on a Si substrate with a ZrO₂ interfacial layer (IL). It is suggested that the ZrO₂ IL below HZO crystallizes in the form of an o-phase prior to HZO crystallization, during rapid thermal annealing, thereby promoting the vertical growth of an o-phase HZO layer. HZO with the ZrO₂ IL consists mainly of an o-phase that exhibits an in-plane tensile stress of 2.68 GPa, resulting in superior ferroelectric characteristics. This technology has the potential to expedite the realization of ferroelectric Hf-based dielectrics in advanced memory and logic technology.

Monoclinic gallium oxide (β-Ga₂O₃) has attracted the interest of the scientific community due to its application in power electronics. Power electronics that need to handle a high voltage often uses a “normally off” device with a positive threshold voltage due to its fail-safe operation and its simple system architecture. In this work, 8-nm-thick Sn-doped polycrystalline β-Ga₂O₃ thin films were investigated as a channel material for power electronics, and their properties were characterized. The optical bandgap of the 8-nm-thick Sn-doped β-Ga₂O₃ was determined to be 5.77 eV, which is larger than that of 100-nm-thick Sn-doped β-Ga₂O₃ due to the quantum confinement effect. The developed back-gated device demonstrated normally off behavior and exhibited a voltage handling capacity as high as 224 V (2.88 MV/cm). This ultrathin β-Ga₂O₃ layer could also be applied to fields other than power electronics, including displays, optical sensors, photocatalytic sensors, and solar cells.

Electrolyte‐gated synaptic transistors (EGSTs) have attracted considerable attention as synaptic devices owing to their adjustable conductance, low power consumption, and multi‐state storage capabilities. To demonstrate high‐density EGST arrays, 2D materials are recommended owing to their excellent electrical properties and ultrathin profile. However, widespread implementation of 2D‐based EGSTs has challenges in achieving large‐area channel growth and finding compatible nanoscale solid electrolytes. This study demonstrates large‐scale process‐compatible, all‐solid‐state EGSTs utilizing molybdenum disulfide (MoS ₂ ) channels grown through chemical vapor deposition (CVD) and sub‐30 nm organic‐inorganic hybrid electrolyte polymers synthesized via initiated chemical vapor deposition (iCVD). The iCVD technique enables precise modulation of the hydroxyl group density in the hybrid matrix, allowing the modulation of proton conduction, resulting in adjustable synaptic performance. By leveraging the tunable iCVD‐based hybrid electrolyte, the fabricated EGSTs achieve remarkable attributes: a wide on/off ratio of 10 ⁹ , state retention exceeding 10 ³ , and linear conductance updates. Additionally, the device exhibits endurance surpassing 5 × 10 ⁴ cycles, while maintaining a low energy consumption of 200 fJ/spike. To evaluate the practicality of these EGSTs, a subset of devices is employed in system‐level simulations of MNIST handwritten digit recognition, yielding a recognition rate of 93.2%.

This research study thoroughly examines the optimal thickness of indium tin oxide (ITO), a transparent electrode, for near-ultraviolet (NUV) light-emitting diodes (LEDs) based on InGaN/AlGaInN materials. A range of ITO thicknesses from 30 to 170 nm is investigated, and annealing processes are performed to determine the most favorable figure of merit (FOM) by balancing transmittance and sheet resistance in the NUV region. Among the films of different thicknesses, an ITO film measuring 110 nm, annealed at 550 °C for 1 min, demonstrates the highest FOM. This film exhibits notable characteristics, including 89.0% transmittance at 385 nm, a sheet resistance of 131 Ω/□, and a contact resistance of 3.1 × 10⁻³ Ω·cm². Comparing the performance of NUV LEDs using ITO films of various thicknesses (30, 50, 70, 90, 130, 150, and 170 nm), it is observed that the NUV LED employing ITO with a thickness of 110 nm achieves a maximum 48% increase in light output power at 50 mA while maintaining the same forward voltage at 20 mA.