https://scholar.dgist.ac.kr/handle/20.500.11750/11853 Mon, 03 Aug 2026 10:20:18 GMT 2026-08-03T10:20:18Z https://scholar.dgist.ac.kr/handle/20.500.11750/60589 Title: Thermally induced structural evolution of diamond surface for pool boiling enhancement Author(s): Kim, Yunseo; Kong, Daeyoung; Park, Jeonghwan; Jang, Bongho; Kim, Taeyeon; Kwon, Hyuk-Jun; Cho, Jungwan; Bin In, Jung; Lee, Hyoungsoon Abstract: Effective thermal management in power devices is essential for energy-efficient operation. Pool boiling dissipates heat effectively through passive phase changes, eliminating the need for pumping power. However, these benefits remain unrealized in high-power-density devices owing to the risk of reaching Critical Heat Flux (CHF). The superior heat-spreading capabilities of diamond can help mitigate excessive heat flux in such devices. Consequently, pool boiling on diamond surfaces represents a promising cooling strategy for devices with high power densities. However, the inherent chemical inertness of diamond severely limits its surface modification, thereby posing significant challenges to the control of interfacial phenomena. This study investigated methods to modify Polycrystalline Diamond (PCD) surfaces to enhance their pool boiling performance. Thermal oxidation efficiently altered the PCD surface, exploiting its unique material properties. The enhanced surface enabled a 47.8% increase in the heat transfer coefficient and a 119.4% increase in the CHF. Additionally, an in-depth investigation clarified how structural and chemical modifications induced by high-temperature oxidation enhanced pool boiling performance. Sat, 28 Feb 2026 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/60589 2026-02-28T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/60546 Title: Inkjet-Printed BaTiO3 Nanoparticle-Embedded Capacitor Array for Physical Unclonable Function Author(s): Hong, Woongki; Bissannagari, Murali; Cho, Youngjae; Jang, Jae Eun; Kwon, Hyuk-Jun; Kang, Hongki Abstract: Nanoparticle (NP)-based physical unclonable functions (PUFs) have attracted attention as a digital fingerprint technology that alternates with microfabrication-based PUFs by utilizing natural randomness at the nanoscale. Mostly NP-based optical PUFs have been proposed due to the absence of nanomaterial fabrication method compatible with microelectronics, but the need for a bulky optical readout system makes it difficult to utilize them in microelectronics. In this work, we developed the NP-based capacitor PUF (CAP-PUF) technology that can be read electrically and integrated into microelectronics while utilizing the benefit of the natural physical randomness of NPs. We incorporated a high-k BaTiO3 NP inkjet printing micropatterning process for the fabrication of the NP-embedded CAP-PUF array. The inkjet-printing parameters have been optimized to maximize the natural randomness of the BaTiO3 NP micropatterns by increasing the intrinsic stochasticity, especially the fluid dynamics that occurring during the multilayer printing. The BaTiO3 NP-embedded CAP-PUF array shows high security performance, showing the inter-hamming distance of 0.52, uniformity of 0.44, entropy of 0.989, and intra-hamming distance up to 0.064. High-k NP inkjet-printing-based CAP-PUFs can provide highly unique digital fingerprints based on the intrinsic randomness in nanoscale for microelectronics. Sun, 31 May 2026 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/60546 2026-05-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/60480 Title: Laser-Induced Oxygen Engineering for Localized Homojunction Formation in SnS2 Photodetectors Author(s): Lee, Jieun; Kim, Junil; Sim, Young-Jun; Lee, Byeongmoon; Jang, Jae Eun; Kwon, Hyuk-Jun Abstract: The development of high-performance optoelectronic devices based on 2D materials has attracted significant attention. However, conventional vertical stacking methods are limited by complex processes and interfacial defects. To overcome these challenges, we propose a simple and efficient one-step process to form an in-plane homojunction within a single n-type tin disulfide (SnS2) flake via direct laser irradiation. The core process, oxidative thinning, utilizes a focused 532 nm laser to locally convert a portion of SnS2 into tin oxide (SnOx). Consequently, an energy barrier arising from a work-function difference of approximately 0.7 eV is formed at the interface, promoting the separation of photogenerated electron-hole pairs. The fabricated photodetector demonstrates a fast response time (tau r/tau f = 474/299 ms), an improvement of several tens of times compared with the pristine SnS2 device. Furthermore, it exhibits a high responsivity (R) of 703 mA W-1, an external quantum efficiency (EQE) of 170%, and a remarkable specific detectivity (D*) of 2.35 x 1014 Jones, along with excellent operational stability. This laser-induced local conversion technique presented can provide a powerful and practical platform for developing next-generation flexible and wearable optoelectronic devices. Thu, 30 Apr 2026 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/60480 2026-04-30T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/60031 Title: Achieving wide-range steep slopes in SnS2 negative capacitance transistors through an isolated band structure and thermionic emission enhancement via Bi contacts Author(s): Song, Chong-Myeong; Park, Jaewoo; Lee, Shinbuhm; Kwon, Hyuk-Jun Abstract: Negative capacitance FETs aim for sub-60 mV dec-1 switching to curb power consumption, but often encounter instability and narrow steep-slope windows. We present a hysteresis-free NCFET that strategically utilizes a 2D SnS2 channel. The inherent isolated conduction band of SnS2, yielding a step-like density of states, is pivotal for sharp turn-on characteristics when effectively coupled with the negative capacitance effect. The SnS2 channel is integrated with an La:HfO2/HfO2 ferroelectric-dielectric gate stack and Bi contacts. This architecture shows an average subthreshold swing of 34 mV dec-1 across four current decades, maintaining sub-60 mV dec-1 operation over this wide range, and enabling sub-0.4 V operation. Bi contact is key, minimizing Fermi-level pinning at the SnS2/metal interface. This expands the thermionic emission region, allowing the negative capacitance to fully leverage the distinct properties of SnS2 for sustained wide-range steep-slope performance. This work demonstrates a novel approach to ultralow-power transistors by integrating an isolated-band semiconductor, optimized ferroelectric, and contact engineering. Sun, 30 Nov 2025 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/60031 2025-11-30T15:00:00Z