https://scholarworks.unist.ac.kr/handle/201301/75 Wed, 08 Apr 2026 21:44:00 GMT 2026-04-08T21:44:00Z https://scholarworks.unist.ac.kr/handle/201301/91143 Title: Strong Fermi-level Pinning Driven by Epitaxial Graphene Interlayer in Metal/4H-SiC Junction Author(s): Hyun, Eunseok; Park, Jungjae; Kim, Junhyung; Jo, Jaehyeong; Kim, Jiwan; Park, Hyunjae; Park, Kibog Abstract: Fermi-level pinning is a phenomenon that the Schottky barrier of metal/semiconductor junction exhibits weak dependence on the metal work-function. According to the previous study [1], the metal/graphene/Si junction exhibits strong Fermi-level pinning which is expected on an ideal metal/Si junction. It has been reported that the Fermi-level pinning of metal/SiC junction is relatively weak compared with the metal/Si junction due to the ionicity between atomic elements of crystalline structure [2]. With this background, we investigated the Fermi-level pinning in metal/graphene/4H-SiC junctions. The junction was fabricated by first epitaxially growing graphene on a 4H-SiC substrate with the metal-capping method under UHV environment [3] and then depositing circular metal (Al, Ni, Pt) electrodes onto the grown graphene layer. The Fermi-level pinning factor S was extracted from current-voltage (I-V) and capacitance-voltage (C-V) curves, signifying strong Fermi-level pinning. A theoretical model proposed by Kopylov et al. describing the charge transfer at the graphene/SiC interface provides a plausible explanation for the observed strong Fermi-level pinning [4]. [1]Hoon Hahn Yoon et al., Nano Letters 17(1), 44 (2017) [2] Stephen Kurtin, T. C. McGill, and C. A. Mead, Physical Review Letters 22, 1433 (1969) [3] Han Byul Jin et al.,Scientific Reports 5, 9615 (2015) [4] Sergey Kopylov et al., Applied Physics Letters 97, 112109 (2010) Sun, 25 Jan 2026 15:00:00 GMT https://scholarworks.unist.ac.kr/handle/201301/91143 2026-01-25T15:00:00Z https://scholarworks.unist.ac.kr/handle/201301/91142 Title: Interface Energy Barrier Inhomogeneity of Pt/4H-SiC Junction Probed with Planar Ballistic Electron Emission Spectroscopy Author(s): Kim, Jiwan; Jo, Jaehyeong; Park, Jungjae; Park, Hyunjae; Hyun, Eunseok; Lee, Jisang; Oh, Sejin; Park, Kibog Abstract: The inhomogeneity of the interfacial energy barrier is associated with crystallographic variations of the interface, which is inevitable in heterojunctions. The ballistic electron emission microscopy/spectroscopy (BEEM/BEES) has been commonly used to observe the local variation of interfacial energy barrier with high spatial resolution (1-10 nm) [1]. However, the tip-related issues [2, 3] and long scanning time make it difficult to investigate the large area reliably. Here, we suggest an experimental methodology utilizing the device version of BEES to estimate the inhomogeneity of interfacial energy barrier with single spectral measurements covering the entire junction area. Our approach (i) relies on the Bell-Kaiser theory [1] for a ‘point’ BEEM response, (ii) treats the tunnel junction as an ensemble of virtual BEEM tips, and (iii) models the second-derivative spectrum (SDS) of the ‘lumped’ BEEM response using a known statistical nature of interfacial barriers [4]. For the case of simple two distinct Schottky barriers (SBs), the working principle of ‘planar BEES’ is illustrated in Fig. 1. To validate our methodology, we apply it to Pt/4H-SiC junction, adopting the Gaussian distribution of interfacial barriers. In its SDS (see Fig. 2), we observe two peaks at 1.60 V and 1.74 V corresponding to two lowest conduction band minima of 4H-SiC located at the M point of the Brillouin zone [5] and the standard deviation of SB is obtained to be 156.7 meV. Our methodology can be used broadly for other heterojunctions as long as the inhomogeneous interface possesses the Gaussian nature. [1] L.D.Bell and W. J. Kaiser, Phys. Rev. Lett. 61, 2368(1988). [2] M. Prietsch and R. Ludeke, Phys. Rev. Lett. 66, 2511 (1991). [3] J. P. Pelz and R. H. Koch, Phys. Rev. B 41, 1212 (1990). [4] R. T. Tung, Phys. Rev. B 45, 13509 (1992). [5] B. Kaczer, H.-J. Im, J. P. Pelz, J. Chen, and W. J. Choyke, Phys. Rev. B 57, 4027 (1998). Mon, 26 Jan 2026 15:00:00 GMT https://scholarworks.unist.ac.kr/handle/201301/91142 2026-01-26T15:00:00Z https://scholarworks.unist.ac.kr/handle/201301/90373 Title: Real Space Imaging of Spin Scattering in Chirality-Induced Spin Selectivity Author(s): Lee, Jaehyun; Jeong, Uiseok; Yan, Binghai; Park, Noejung; Namgung, Seon Mon, 01 Dec 2025 15:00:00 GMT https://scholarworks.unist.ac.kr/handle/201301/90373 2025-12-01T15:00:00Z https://scholarworks.unist.ac.kr/handle/201301/90285 Title: Chiral-induced Spin Selectivity in the Presence of Weak Spin-orbit Coupling Author(s): Plenio, Martin. B.; Park, Noejung Tue, 05 Aug 2025 15:00:00 GMT https://scholarworks.unist.ac.kr/handle/201301/90285 2025-08-05T15:00:00Z