http://scholar.dgist.ac.kr:80 The Repository digital repository system captures, stores, indexes, preserves, and distributes digital research material. 2026-07-17T17:47:55Z https://scholar.dgist.ac.kr/handle/20.500.11750/60454 Title: High-Gain Ag2Te/MoS2 Hybrid Photodetectors for Short-Wave Infrared Imaging Author(s): Jeong, Seock-Jin; Ko, Hyun Woo; Jo, Suyeon; Selvaraj, Joicy; Kim, Jung-Min; Lee, Namji; Ahn, Jae-Hyeon; Lee, Hyeonchae; Jeong, Seungmin; Kim, Heedae; Seo, Paul Hongsuck; Shim, Jae Won; Kim, Yonghun; Ra, Hyun-Soo; Park, Min-Chul; Lee, Jong-Soo Abstract: Physical artificial intelligence has emerged as a pivotal component in next-generation humanoid technologies, including advanced optical sensors, as it enables autonomous acquisition of sensory information. This study reports a high-performance 0D/2D hybrid photodetector using a high-gain Ag2Te/MoS2 hybrid structure for visible to short-wave infrared (SWIR) photodetection, achieved by the absorption of Ag2Te quantum dots in the infrared region (similar to 1450 nm). The Ag2Te/MoS2 photodetector exhibits a high photoresponsivity of around 7.5 & times; 105 AW-1 and a specific detectivity of over 9.9 & times; 108 Jones at 1 & micro;W/cm2 illumination power with a 0.2 V drain bias voltage. Furthermore, depending on the gain of the photodetector, a fast response speed can also be achieved, with rise and decay times as short as 13 and 23 ms. The 0D/2D hybrid devices were successfully implemented in a 32 & times; 32 array format for infrared imaging, with the results demonstrating spatially resolved pattern reconstruction and real-time photoresponse acquisition. By hybridizing quantum dots and 2D materials, the developed photodetector has broad potential applications, including use in highly integrated SWIR image sensors. 2026-03-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/60453 Title: Electrically Tunable Tunneling and Spectral Response in WSe2/h-BN/CdSe/Graphene Heterostructure Author(s): Lee, Sang-Hyeon; Teku, Justice Agbeshie; Jeong, Min-Hye; Ahn, Jae-Hyeon; Chae, Weon-Sik; Kwak, Do-Hyun; Lee, Jong-Soo Abstract: Mixed-dimensional heterostructures consisting of zero- and two-dimensional materials offer a promising platform for optoelectronic devices, as the versatility of material combination allows tunable optical properties. Bias-induced approaches provide an additional means to tune the optical properties beyond the intrinsic band alignment of van der Waals junctions. Here, bias-induced tunneling characteristics are achieved in vertically stacked WSe2/h-BN/CdSe quantum dots/graphene heterostructures by employing the top graphene electrode to regulate carrier transport across the h-BN barrier. The electrical analyses based on the Simmons approximation demonstrate tunneling-mediated charge transfer through thin h-BN layers and bias-dependent modulation of the barrier height. Furthermore, tunneling-induced exciton dissociation in WSe2 and CdSe QDs is observed through spectral responsivity and scanning photocurrent measurements. This work establishes a voltage-dependent tunneling platform that enables deterministic control of carrier dynamics in mixed-dimensional optoelectronic devices. 2026-04-30T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/60452 Title: The anatomy of magnetic field pulse induced transverse domain wall dynamics Author(s): Cho, Jaehun; Yun, Won Seok; Kim, June-Seo Abstract: The microscopic anatomy of the precessional torque-induced magnetic domain wall racetrack memory is numerically investigated. A systematic analysis is performed to explain the efficiency and limitations of this domain wall motion architecture. A transverse domain wall in an in-plane magnetic nanowire is chosen, and the direction of the applied magnetic field is applied to be perpendicular to the film plane. The domain wall displacement upon the application of an out-of-plane magnetic field pulses is shown to be driven by the precessional torque and subsequently decelerated by the damping torque, causing the domain wall to settle at a specific position. Crucially, a characteristic frequency is exhibited by this domain wall dynamics. After removing the magnetic field, a reverse domain wall dynamics is observed with the same frequency, causing the domain wall to revert to its original position. To realize continuous domain wall motion, a notch structure is introduced, and the depinning field is calculated as a function of the out-of-plane field strength. The analysis reveals that the depinning field decreases linearly as the out-of-plane field strength increases. Finally, the principle of domain wall hopping in a multiple-notched nanowire is verified by the application of sequential out-of-plane field pulses. © The Author(s) 2026. 2026-03-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/60451 Title: Polarity-Programmable Bismuth Oxide Overlayers on Bi(111)/MoS2 Heterostructures via Oxidation and Annealing Author(s): Han, Sang Wook; Yun, Won Seok; Seong, Seungho; Kang, Jeongsoo; Ko, Minji; Ryu, Sunmin; Kim, Yong Soo Abstract: Band-structure engineering in bismuth (Bi) oxides is frequently hampered by their amorphous or poorly ordered nature, which obscures the relationship among stoichiometry, band dispersion, and transport polarity. We find that native BiOx overlayers on epitaxial Bi(111)/MoS2 undergo a reversible n → p → n polarity control of the heterostructure system under controlled air exposure and annealing. As-grown BiOx-rich surfaces are n-type and exhibit a photoluminescence peak at ∼2.1–2.2 eV. Mild air annealing (100 °C, 1 h) of native BiOx overlayers on epitaxial Bi(111)/MoS2 yields a p-type surface with a phase-mixed Bi2O3 (α+β) overlayer, characterized by a highly dispersive Bi–O valence band, and in-situ annealing at 300 °C reduces the thickness of the oxide layer and restores the n-type band alignment governed by the Bi(111)/MoS2 stack. First-principles calculations for hexagonal Bi2O3 monolayers and Bi2O3/Bi(111) heterostructures reveal a transition from a wide-gap, O-2p-dominated oxide to a narrow, Bi-dominated direct gap at Γ, which supports the observed p → n band structure evolution. These findings provide a fundamental mechanism for tuning the polarity and band alignment of Bi-oxide-based interfaces on 2D semiconductors. © 2026 American Chemical Society 2026-04-30T15:00:00Z