https://scholarworks.unist.ac.kr/handle/201301/97 2026-04-17T06:46:08Z https://scholarworks.unist.ac.kr/handle/201301/91349 Title: Indium Tin Oxide Vertical Channel Transistors for Scaled 4F2 2T0C Gain Cell Memory With Etched Sidewall Cleaning Author(s): Gu, Hyeonho; Jung, Haksoon; Park, Minho; Lee, Hyeonjin; Choi, Ae Rim; Oh, Il-Kwon; Zhao, Yanfeng; Kim, Byungjo; Kim, Jungsik; Jang, Byung Chul; Lee, Yongwoo; Kwon, Jimin Abstract: 2T0C gain cell memory based on amorphous oxide semiconductor vertical channel transistors (VCTs) has emerged as a promising high-density embedded dynamic access memory solution for memory-centric computing systems, monolithically integrated atop silicon logic. This capacitor-less memory offers long retention time and a compact 4F(2) cell footprint, enabling low-power and area-efficient integration above logic circuits. In this work, amorphous indium tin oxide VCTs and 2T0C gain cells with hole diameters scaled down to 150 nm were fabricated. However, scaling the hole diameter caused residual etch by-products to accumulate along the channel sidewalls, degrading the subthreshold swing and on-state current. To mitigate this issue, a sidewall cleaning process was introduced to effectively remove the residues. The treatment improved the VCT on-state current by over three orders of magnitude and enabled stable single- and two-bit memory operation with retention time exceeding 160 s. 2026-03-31T15:00:00Z https://scholarworks.unist.ac.kr/handle/201301/91340 Title: Anomalous Pressure-Temperature Ultrahigh Sensitivities in Atomically Engineered Carbonitride MXenes for Multifunctional Wearable Human-Machine Interfaces: Joint Computational-Experimental Elucidations Author(s): Mohapatra, Debananda; Han, Ju-Hyoung; Kang, Hyun Jin; Byun, Jeong Eun; Lee, Seonghun; Lee, Sanghyuk; Son, Yeseul; Park, Jaeeun; Shin, Tae Joo; Kang, Youngho; Lee, Jung Woo; Kwon, Soon-Yong; Kim, Soo-Hyun Abstract: In the era of autonomous systems and multifunctional devices, sensors serve as vital sensory components in our Internet of Things and technologically advanced society. At the end of the synthetic 2D nanomaterials research, MXenes are not just chemicals but materials, depending on how they are synthesized for targeted applications, such as dual-functional temperature and pressure-sensitive wearable sensing. The current findings introduce the potential strategic role of nitrogen atoms to the Ti-Carbonitride (Ti3CNTz) structure in a controlled compositional stoichiometry of Ti3C1.8N0.2Tz, Ti3C1.5N0.5Tz, Ti3CNTz, Ti3C2Tx to deliver an ultrahigh sensitivity (300%-400% temperature & pressure sensitivity enhancement) and durability in real-time human-machine sensing interface applications. These recorded outstanding dual-sensing performance outplays many other MXene stoichiometries, graphene-related 2D nanomaterials, and their associated composites. Synchrotron radiation-based X-ray absorption fine structure and density functional theory analysis reveal that incorporating low N content (e.g., Ti3C1.8N0.2Tz) enhances temperature sensitivity by boosting electrical conductivity, and an upshift in the vibrational spectrum with increased lattice deformability significantly improves pressure sensitivity. We provide valuable insights for developing advanced sensing materials, emphasizing the need to investigate the fundamental mechanisms that control the interactions among layered 2D MXene materials and the sensing device functions that bridge human and machine interfaces. 2026-03-31T15:00:00Z https://scholarworks.unist.ac.kr/handle/201301/91333 Title: Comparative Growth and Functional Integration of CeO2 Films via Plasma-Enhanced and Thermal ALD Using a Tailored Cerium Precursor for Artificial Synaptic Devices Author(s): Seo, Yewon; Mohapatra, Debananda; Moon, Sola; Bae, Jong-Seong; Cheon, Taehoon; Yoon, Tae-Sik; Kim, Soo-Hyun Abstract: The development of high-performance switching cerium dioxide (CeO2) thin films is critical for advancing neuromorphic computing technologies, where atomic layer deposition (ALD) offers unparalleled control over the conformality, stoichiometry, and microstructure of oxide thin films. Here, we report the CeO2 deposition using a newly developed heteroleptic amidinate framework liquid precursor, bis(n-propylcyclopentadienyl)(N,N '- diisopropylpropionamidinato)Ce(III)[(n-PrCp)2(iPr2-pamd)Ce(III)], via thermal ALD (Th-ALD) and plasma-enhanced ALD (PE-ALD) processes with O2 and O2 plasma coreactants, respectively. Both methods were optimized at 200 degrees C, achieving growth per cycle values of 1.7 & Aring;/cycle (Th-ALD) and 1.2 & Aring;/cycle (PE-ALD), which revealed striking contrasts in film properties. PE-ALD produced highly crystalline cubic CeO2 with larger grains (similar to 7 nm), higher density (similar to 7.1 g/cm3), and greater surface roughness (similar to 1.1 nm), while Th-ALD yielded nanocrystalline, smoother, and less dense films. X-ray photoelectron spectroscopy confirmed near-stoichiometric Ce1O2.1 composition without detectable impurities for PE-ALD, whereas Th-ALD films were oxygen-deficient (Ce1O0.8) and carbon-contaminated. Optical analysis revealed a refractive index of 2.5 and a well-defined bandgap (3.2 eV) for PE-ALD films, compared to 1.8 for Th-ALD. Despite reduced step coverage (similar to 56%) on high-aspect-ratio features compared to Th-ALD (excellent conformality, similar to 100%), only PE-ALD-CeO2 enabled analog resistive switching in Pt/CeO2/Pt devices, demonstrating synaptic behavior essential for neuromorphic computing. Notably, the PE-ALD-CeO2 device achieved a high dynamic range (a resistance ratio of 7.6 & times; 102), underscoring the importance of oxygen-vacancy-mediated analog synaptic weight updates via plasma-activated ALD for reliable artificial synapse functionality. These findings reveal how precursor chemistry and plasma processes govern film quality and synaptic behavior, offering a scalable route to oxide-based artificial synaptic devices. 2026-02-28T15:00:00Z https://scholarworks.unist.ac.kr/handle/201301/91326 Title: Wafer-Scale Single-Crystal Boron Nitride: Synthesis and Integration in 2D Electronics Author(s): Wang, Jaewon; Kwon, Soon-Yong Abstract: Hexagonal boron nitride (hBN) has become a cornerstone dielectric and encapsulation material for next-generation 2D electronics. Its atomically flat surface, wide bandgap, chemical stability, low trap density, and high in-plane thermal conductivity collectively enhance carrier mobility, suppress Coulomb and remote phonon scattering, and enable efficient heat dissipation across a range of 2D devices. Translating these properties into practical technologies demands wafer-scale synthesis of hBN films with precise control over thickness, crystallographic orientation, and stacking sequence, along with integration schemes compatible with semiconductor manufacturing. This Review highlights recent advances in scalable vapor-phase synthesis of hBN, emphasizing self-limiting growth mechanisms and epitaxial strategies that yield single-crystalline and stacking-engineered films. We discuss transfer and direct-integration methods for embedding hBN into 2D architectures and correlate synthesis parameters with device-level metrics. Key challenges and future directions are outlined for establishing hBN as a manufacturable platform for high-performance, wafer-scale 2D electronics. 2026-02-28T15:00:00Z