https://scholarworks.unist.ac.kr/handle/201301/98 2026-05-09T00:20:54Z 2026-05-09T00:20:54Z Rahmatulloh, Imasda Dalayoan, Daryll J. C. Ali, Asad Shin, Soobeom Nguyen, Anh T. D. Kwon, Taenam Behera, Satyabrat Lee, Jaehyun Kim, Heekyeong Jeong, Hu Young Namgung, Seon Yi, Gyu-Chul Chung, Kunook https://scholarworks.unist.ac.kr/handle/201301/91637 2026-05-06T05:30:18Z 2026-03-31T15:00:00Z

Title: Epitaxial n-ZnO/MoS2/p-GaN Heterostructure Light-Emitting Diodes Author(s): Rahmatulloh, Imasda; Dalayoan, Daryll J. C.; Ali, Asad; Shin, Soobeom; Nguyen, Anh T. D.; Kwon, Taenam; Behera, Satyabrat; Lee, Jaehyun; Kim, Heekyeong; Jeong, Hu Young; Namgung, Seon; Yi, Gyu-Chul; Chung, Kunook Abstract: We investigated an epitaxial strategy for fabricating MoS2 light-emitting diodes (LEDs). A full-coverage MoS2 active layer was grown on p-type GaN, and n-type ZnO nanorods were then vertically aligned on the MoS2 to form a p-n junction with negligible damage to the MoS2. All materials have nearly matched hexagonal structures, enabling single-crystal alignment. Although the continuous MoS2 film formed multiple layers (MLs), the ZnO/MoS2/GaN heterostructure yielded favorable optical characteristics of the ML-MoS2, including internal quantum efficiency comparable to that of the single-layer MoS2. The ZnO/MoS2/GaN LED exhibited stable A and B exciton emissions, which imply direct bandgap transition with spin-orbit coupling. Without mechanically exfoliated or transferred 2D films, this epitaxial approach satisfies the key requirements for fabricating 2D-based optoelectronic and quantum light sources. The strength of epitaxy, such as large-scale scalability and multiple quantum-well formation, will further advance 2D optoelectronics, making them more practical and efficient.

2026-03-31T15:00:00Z Cho, Yongjin Kim, Su Jae Jung, Min-Hyoung Lee, Yousil Jeong, Hu Young Kim, Young-Min Lee, Hu-Jong Kim, Seong-Gon Jeong, Se-Young Lee, Gil-Ho https://scholarworks.unist.ac.kr/handle/201301/91628 2026-05-06T02:30:35Z 2026-02-28T15:00:00Z

Title: Ballistic transport in nanodevices based on single-crystalline Cu thin films Author(s): Cho, Yongjin; Kim, Su Jae; Jung, Min-Hyoung; Lee, Yousil; Jeong, Hu Young; Kim, Young-Min; Lee, Hu-Jong; Kim, Seong-Gon; Jeong, Se-Young; Lee, Gil-Ho Abstract: In ballistic transport, the movement of charged carriers remains unimpeded by scattering events. In this limit, microscopic parameters such as crystal momentum, spin and quantum phase are well conserved, allowing electrons to maintain their quantum coherence over longer distances. Nanoscale materials, such as carbon nanotubes, graphene, and nanowires, can exhibit ballistic transport. However, their scalability in devices is significantly limited. While deposited metal films offer scalability for nanodevices, their short electronic mean free paths hinder ballistic transport. In this study, we investigated the electronic transport in cross-geometry devices fabricated with 90-nm-thick Cu films without grain boundaries. We demonstrated ballistic transport in devices with channel widths of 150 nm at temperatures below 85 K via negative bend resistance measurements. Our findings establish a scalable platform for exploring the intrinsic quantum mechanical properties of Cu, advancing both the fundamental understanding of quantum transport in metals and its practical applications in next-generation electronic quantum technologies.

2026-02-28T15:00:00Z Park, Yae Eun Han, Hyunjin Jung, Sung-Jin Song, Junwoo Kim, Jino Na, Jungwon Kim, Kwangjoo Lee, Insub Wee, Hoon Lee, Joonhyun Yang, Sungjun Jo, Seungki Lee, Ho Seong Shin, Tae Joo Koh, Youngdeog Son, Jae Sung https://scholarworks.unist.ac.kr/handle/201301/91598 2026-04-28T00:30:22Z 2026-03-31T15:00:00Z

Title: Interface-engineered melt-spun BiSbTe for multiscale phonon scattering and enhanced thermoelectric performance Author(s): Park, Yae Eun; Han, Hyunjin; Jung, Sung-Jin; Song, Junwoo; Kim, Jino; Na, Jungwon; Kim, Kwangjoo; Lee, Insub; Wee, Hoon; Lee, Joonhyun; Yang, Sungjun; Jo, Seungki; Lee, Ho Seong; Shin, Tae Joo; Koh, Youngdeog; Son, Jae Sung Abstract: Thermoelectric materials have attracted tremendous attention owing to their ability to directly convert heat into electricity. Enhancing the thermoelectric efficiency of materials relies on minimizing thermal conductivity via phonon scattering engineering, where the broad spectrum of phonon frequencies requires multiscale architectures capable of scattering phonons over diverse wavelengths. In this study, we developed BiSbTe-based thermoelectric materials featuring multiscale hierarchical microstructures, achieved via melt-spinning synthesis of nanostructured BiSbTe particles followed by solution-phase coating with polyoxometalates (POMs). During spark plasma sintering, the POM surface layers decompose to form ultrathin oxide interfacial layers within the BiSbTe grains. These oxide interfaces, in combination with nanoscale features, effectively suppress lattice thermal conductivity to 0.38 W m-1 K-1 at room temperature with only 0.1 mol% POM additive, yielding a peak figure of merit (ZT) of 1.56 at 75 degrees C. This work demonstrates a scalable strategy for realizing multiscale phonon scattering and enhanced thermoelectric performance through interface engineering.

2026-03-31T15:00:00Z Nam, Kisoo Niu, Chang Jang, Hyeongjun Park, Beomjin Park, Yoonju Lee, Youngjoon Jeong, Changwook Ye, Peide https://scholarworks.unist.ac.kr/handle/201301/91596 2026-04-27T06:00:02Z 2026-02-28T15:00:00Z

Title: Characterization of Thermal Stability and Unexpected Mobility Enhancement in IGZO FETs Measured up to 750°C. Author(s): Nam, Kisoo; Niu, Chang; Jang, Hyeongjun; Park, Beomjin; Park, Yoonju; Lee, Youngjoon; Jeong, Changwook; Ye, Peide Abstract: In this work, we report the in-situ high-temperature electrical characteristics of atomic-layerdeposited (ALD) InGaZnO (IGZO) field-effect transistors (FETs). Transfer characteristics of IGZO FETs are measured up to 750 ◦C, where crystallization of the gate dielectric leads to degradation of transistor switching performance. Remarkably, the oxide channel material remains functional, and the FETs exhibit minimal degradation after 90 minutes at 600 ◦C, demonstrating the exceptional thermal stability of channel performance. An unexpected mobility enhancement is observed with increasing temperature. With the peak field-effect mobility (—FE) of 154 cm2V −1s −1 at 550 ◦C, this temperature-dependence contrasts with that of conventional single-crystal wide bandgap materials. The mobility enhancement is consistent with our nanocrystalline mobility model, which incorporates grain boundary (GB) scattering. At elevated temperatures, de-trapped defects transition into trapped states that no longer capture carriers, reducing the energy barrier (Eb) at the grain boundaries and enhancing mobility. Furthermore, the contact resistance (Rc) and sheet resistance (Rsh) are reduced by 81% and 72%, respectively, at 600 ◦C. This result underscores the strong potential of ALD oxide semiconductor FETs for Dynamic Random Access Memory (DRAM) and extreme-environment electronics.

2026-02-28T15:00:00Z