Silicon carbide (SiC) is one of the hottest semiconductor materials for use in high-power, high-temperature, and high-frequency electronic devices because of its wide bandgap, high breakdown electric field, high thermal conductivity, and device-applicable mobility of carriers [1]. Many kinds of structural defects were reported in 4H-SiC SiC substrates and epitaxial layers. Most of common defects in SiC materials are threading dislocations (TDs), basal plane dislocation (BPDs), and basal plane stacking faults (BSF) [1]. There are numerous studies on BSFs in 4H-SiC epitaxial layers and recently we reported investigations on Shockley-type and Frank-type stacking faults based on photoluminescence mapping and by high-angle annular dark-field (HAADF) high-resolution scanning transmission electron microscopy (HR-STEM) [2-3]. In addition to BSFs, there is other type of stacking fault, which is not existing on basal plane, called to prismatic stacking fault (PSF). Performance limiting surface defect in SiC p-n junction diode in 4H-SiC epitaxial layers was first reported as by T. Kimoto et al in 1999 and named to the carrot-like groove [4]. The carrot defect is one of the surface morphological defects in 4H-SiC epitaxial layers [4] and has been reported to the so-called killer defect, which strongly deteriorate SiC-based various devices [1]. In 4H-SiC, the PSF was reported in 2005 by M. Benamara et al. in studying a so-called carrot defect [6]. They concluded that the carrot defect consists of two intersecting planar faults on prismatic {1"1" ̅00} and basal {0001} planes. The PSF and the BSF are connected by a stair-rod dislocation at the crossover. J. Hassan et al. [7] systematically investigated various kinds of carrot defects and suggested the origins of the carrot defect. In this work, we investigated abnormal carrot defect which showed disconnected two surface groove lines and report buried PSF structure in the carrot, for the first time. Detailed structures of PSFs and BSFs inside the carrot defect were systematically investigated by HAADF HR-STEM. Fig. 1(a) and (b) show normal and abnormal carrot defects, respectively, and Fig. 1(c) shows typical zigzag feature of the PSF in the carrot defect. The normal carrot defect has one surface groove line connected from head to tail of the carrot. The abnormal carrot defect has two disconnected surface groove lines as shown in Fig. 1(b). At the region where the surface groove was disconnected we observed buried PSF inside the epitaxial layer as shown in Fig. 2(a). The buried PSF was not terminated on the surface, therefore, it inevitably could not from the surface groove. Fig. 2(b) shows HAADF HR-STEM image for the crossover pointe at the buried PSF and BSF of Fig. 2(a). Our finding implies that the PSF is existing from the head to the tail of the carrot defect even the surface groove was disappearing on the morphological surface defect of carrot. Detailed and systemic investigations of whole PSF and BSF structures with four crossover points and Burgers vectors for the relating stair-rod dislocations will be presented. This work was supported by the Technology Development Program (Republic of Korea, No. 23A02029) funded by the Ministry of SMEs and Startups (MSS, Korea).[1] T. Kimoto, Jpn. J. Appl. Phys. 54, 040103 (2015) [2] M. Na, W. Bahng, H. Jung, C. Oh, D. Jang, S.-K. Hong, Mater. Sci. Semicond. Process. 175, 108247 (2024). [3] M. Na, W. Bahng, H. Jung, C. Oh, D. Jang, S.-K. Hong, Appl. Phys. Lett. 124, 152109 (2024). [4] T. Kimoto, N. Miyamoto, and H. Matsunami, IEEE Electron Device Lett.,46, 471 (1999) [5] T. Kimoto, Z. Y. Chen, S. Tamura, S. Nakamura, N. Onojima, and H. Matsunami, Jpn. J. Appl. Phys., Part 1 40, 3315 (2001) [6] M. Benamara, X. Zhang, M. Skowronski, P. Ruterana, G. Nouet, J. J. Sumakeris, M. J. Paisley, and M. J. O’Loughlin, Appl. Phys. Lett., 86, 021905 (2002). [7] J. Hassan, A. Henry, P. J. McNally, and J. O. Bergman, J. Crystal Growth 312, 1828 (2010).