Silicon Carbide Doping by Ion Implantation


Silicon Carbide Doping by Ion Implantation

Philippe Godignon, Frank Torregrosa, Konstantinos Zekentes

Ion implantation allows incorporating dopants, or atoms in general, in specific areas of the semiconductor surface. This technique is extensively used in silicon technologies for all kind of devices and circuits integration. An ion implanter is a highly complex machine, with many parameters to set-up. In addition, ion implantation process is always associated with an activation thermal annealing used for the dopants incorporation in the crystal. As we will see in this chapter, the implantation and activation processes in silicon carbide require significantly different parameters than in silicon, and it is today a limiting factor in the development of SiC devices mass volume production. The chapter starts with a short introduction on ion implantation, which is followed by an overview of the current SiC ion implantation technology. A detailed presentation of all aspects of SiC ion implantation is presented in the remaining parts. More precisely, it is presented the use of different elements as p- and n-type implanted dopants, the optimum hot implantation conditions for the different elements, the post-implantation annealing, which is still subject of intense studies, the important in SiC channeling effect and the various physical characterization methods of the implanted SiC material. The main part of the present chapter deals with the 4H-SiC polytype, as it is the mostly used polytype for device fabrication.

Silicon Carbide, Implantation, Dopants Activation, Post-Implantation Annealing, Channeling, Implantation Modeling

Published online 2/15/2020, 68 pages

Citation: Philippe Godignon, Frank Torregrosa, Konstantinos Zekentes, Silicon Carbide Doping by Ion Implantation, Materials Research Foundations, Vol. 69, pp 107-174, 2020


Part of the book on Advancing Silicon Carbide Electronics Technology II

[1] R.G Wilson, The Pearson IV distribution and its application to ion implanted depth profiles. Radiat. Eff., 46, 141 (1980).
[2] R. Simonton, D. Kamenista, A. Ray, C. Park, K. Klein, A. Tasch, Channeling control for large tilt angle implantation in Si 〈100〉, Nucl. Instrum. Methods Phys. Res. B, vol 55, 39 (1991).
[3] M. G. Grimaldi, L. Calcagno, P. Musumeci, N. Frangis and J. Van Landuyt, Amorphization and defect recombination in ion implanted silicon carbide, J. Appl. Phys., 81, 7181 (1997).
[4] T. Tsukamoto, M.Hirai, M.Kusaka, M.Iwami, T.Ozawa, T.Nagamura, T.Nakata, Annealing effect on surfaces of 4H(6H)-SiC(0001) Si face, Appl. Surface Sci., Vol 113–114, pp. 467-471, (1997).
[5] A. Hallen, M.S. Janson, A.Yu. Kuznetsov, D. Aberg, M.K. Linnarsson, B.G. Svensson, P.O. Persson, F.H.C. Carlsson, L. Storasta, J.P. Bergman, S.G. Sridhara, Y. Zhang, Ion implantation of silicon carbide, Nucl. Instr. Meth. Phys. Res. B, 186, 186–194, (2002).
[6] T. Troffer, M. Schadt, T.Frank, H. Itoh, G. Pensl, J. Heindl, H. P. Strunk, M. Maier, Doping of SiC by implantation of boron and aluminum, Phys. Stat. Solidi A, 162, 277-298 (1997).<277::AID-PSSA277>3.0.CO;2-C
[7] L. S. Robertson and K. S. Jones, Annealing kinetics of {311} defects and dislocation loops in the end-of-range damage region of ion implanted silicon, J. Appl. Phys., 87, 2910 (2000).
[8] T. Kimoto, J. A. Cooper, Fundamentals of silicon carbide technology: growth, characterization, devices and applications, John Wiley & Sons Singapore Pte. Ltd, (2014).
[9] M. Bockstedte, A. Mattausch, and O. Pankratov, Solubility of nitrogen and phosphorus in 4H-SiC: A theoretical study, Appl. Phys. Lett., Vol. 85(1), pp. 58-60, (2004).
[10] A. Hallen, R. Nipoti, S. E. Saddow, S. Rao and B. G. Svensson, Advances in Silicon Carbide Processing and Applications, Eds. S. E. Saddow and A. Agarwal, Artech House, Inc., Norwood Ma, p.109, (2004,).
[11] A. Schoener, Ion implantation and diffusion in SiC, in “Process Technology for Silicon Carbide Devices”, C-M Zetterling (Ed.) INSPEC, London, pp.51-84, (2002).
[12] F. Schmid, T. Frank, G. Pensl, Experimental Evidence for an Electrically Neutral (N-Si)-Complex Formed during the Annealing Process of Si+-/N+-Co-Implanted 4H-SiC, Mater. Sci. Forum, Vols 483-485 p.641-644, (2005).
[13] F. Schmid, M. Laube, G. Pensl, G. Wagner, M. Maier, Electrical activation of implanted phosphorus ions in [0001]- and [11–20]-oriented 4H-SiC, J. Appl. Phys., Vol. 91p. 9182-9186, (2002).
[14] R. Rurali, E. Hernandez, P. Godignon, R. Rebollo, P. Orderjon, Mater. Sci. Forum, 433-436, 649-652 (2003).
[15] S. Blanqué, J. Lyonnet, J. Camassel, R. Perez, P. Terziyska, S. Contreras, P. Godignon, N. Mestres, J. Pascual, Mater. Sci. Forum, vols. 483-485 pp. 645-648 (2005).
[16] H. Fujihara, J. Suda, T. Kimoto, Electrical properties of n- and p-type 4H-SiC formed by ion implantation into high-purity semi-insulating substrates, Jpn. J. Appl. Phys., 56, 070306 (2017).
[17] R. Nipoti, A. Nath, S. Cristiani, M. Sanmartin, M. V. Rao Mater. Sci. Forum, Vols. 679-680 pp. 393-396 (2011) and in M. V. Rao, A. Nath, S. B. Qadri, Y. L Tian, R. Nipoti, AIP proceedings CP1321 pp.241-244 (2010).
[18] S. Blanqué, Optimisation de l’implantation ionique et du recuit thermique pour SiC, PhD Thesis (2004), University of Montpellier II.
[19] H Bracht, N.A. Stolwijk, M. Laube, and G. Pensl, (2000). Appl. Phys. Lett., 77, 3188 and M. Bockstedte, A. Mattausch, and O. Pankratov, Different roles of carbon and silicon interstitials in the interstitial-mediated boron diffusion in SiC. Phys. Rev. B, 70, 115203, (2004).
[20] Y. Tanaka N. Kobayashi, H. Okumura, R. Suzuki, T. Ohdaira, M. Hasegawa, M. Ogura, S. Yoshida, H. Tanoue, Electrical and Structural Properties of Al and B Implanted 4H-SiC, Mater. Sci. Forum 338-342 pp. 909-912, (2000).
[21] T. Kimoto, A. Itoh, N. Inoue, O. Takemura, T. Yamamoto, T. Nakajima, and H. Matsunami, Conductivity Control of SiC by In-Situ Doping and Ion Implantation, Mater. Sci. Forum 264-268, pp. 675-678 (1998).
[22] Y. Negoro, T. Kimoto, H. Matsunami, Technological Aspects of Ion Implantation in SiC Device Processes, Mater. Sci. Forum, Vols. 483-485 pp. 599-604 (2005).
[23] R. Nipoti, A. Nath, M. V. Rao, A. Hallen, A. Carnera, and Y. L. Tian, “Microwave Annealing of Very High Dose Aluminum-Implanted 4H-SiC”, Appl. Phys. Express 4, 111301 (2011).
[24] R. Nipoti, A. Hallén, A. Parisini, F. Moscatelli, S. Vantaggio Al+ Implanted 4H-SiC: Improved Electrical Activation and Ohmic Contacts, Mater. Sci. Forum 740-742 767 (2013).
[25] V. Heera, W. Skorupa, J. Stoemenos, B. Pécz, High Dose Implantation in 6H-SiC Mater. Sci. Forum, 353-357 pp.579-582 (2001).
[26] E. Wendler, A. Heft, W. Wesh, Ion-beam induced damage and annealing behaviour in SiC, Nucl. Instr. Meth. Phys. B, Vol. 141(1-4), p105-117 (1998).
[27] S. Seshadri, G. W. Eldridge, and A. K. Agarwal, Comparison of the annealing behavior of high-dose aluminum-, and boron implanted 4H–SiC, Appl. Phys. Lett. 72, 2026, doi: 10.1063/1.121681 (1998).
[28] A. Hallén, M. Linnarsson, Ion implantation technology for silicon carbide, Surf. Coat. Technol., 306 pp. 190–193, (2016).
[29] S. Morata, G. Mathieu, F. Torregrosa, G. Boccheciampe, L. Roux, G. Grosset, IMC-200 Series from IBS: Ion Implantation solution for SiC doping, Book of abstracts, ECSCRM’2012.
[30] J.F. Michaud, X. Song, J. Biscarrat, F. Cayrel, E. Collard, D. Alquier, Aluminum Implantation in 4H-SiC: Physical and Electrical Properties, Mater. Sci. Forum 740-742, pp. 581-584, (2012).
[31] R. Nipoti, Post-Implantation Annealing of SiC: Relevance of the Heating Rate, Mater. Sci. Forum, Vols 556-557 pp. 561-566, (2007).
[32] M. Lazar, C. Raynaud, D. Planson, M. L. Locatelli, K. Isoird, L. Ottaviani, J. P. Chante, R. Nipoti, A. Poggi, G. Cardinalli, A Comparative Study of High-Temperature Aluminum Post-Implantation Annealing in 6H- and 4H-SiC, Non-Uniform Temperature Effects, Mat. Sci Forum, Vols 389-393 pp. 827-830, (2002).
[33] H. Wirth, D. Panknin, W. Skorupa, Efficient p-type doping of 6H-SiC: Flash-lamp annealing after aluminum implantation, Appl. Phys. Lett., vol 74, nº7 pp.979-981, (1999).
[34] M. V. Rao “Ultra-Fast Microwave Heating for Large Bandgap Semiconductor Processing” in Advances in Induction and Microwave Heating of Mineral and Organic Materials, ISBN 978-953-307-522-8 Edited by: Stanisław Grundas, Publisher: InTech, (2011).
[35] Y. Negoro, T. Kimoto, H. Matsunami, F. Schmid, and G. Pensl, Electrical activation of high-concentration aluminum implanted in 4H-SiC. J. Appl. Phys., 96, 4916, (2004).
[36] R. Nipoti, A. Hallén, A. Parisini, F. Moscatelli, S. Vantaggio, Al+ implanted 4H-SiC: improved electrical activation and ohmic contacts, Mater. Sci. Forum 740-742 pp. 767-772 (2013).
[37] A. Parisini, M. Gorni, A. Nath, L. Belsito, M. V. Rao, and R. Nipoti, Remarks on the room temperature impurity band conduction in heavily Al+ implanted 4H-SiC, J. Appl. Phys. 118, 035101 (2015).
[38] R. Nipoti, A. Parisini, S. Vantaggio, G. Alfieri, U. Grossner, E. Centurioni, 1950°C Annealing of Al+ Implanted 4H-SiC: Sheet Resistance Dependence on the Annealing Time, Mater. Sci. Forum, Vol. 858, pp.523-526, (2016).
[39] Y.D. Tang, H.J. Shen, Z.D. Zhou, X.F. Zhang, Y. Bai, C.Z. Li, Z.Y. Peng, Y.Y. Wang, K.A. Liu, X.Y. Liu Book of abstracts, ICSCRM’2015.
[40] H. M. Ayedh, R. Nipoti, A. Hallén and B. G. Svensson, Controlling the Carbon Vacancy Concentration in 4H-SiC Subjected to High Temperature Treatment, Mater. Sci. Forum, vol 858 pp. 414-417, (2016).
[41] C. Dutto, E. Fogarassy, D. Mathiot, D. Muller, P. Kern, D. Ballutaud, Long-pulse duration excimer laser annealing of Al+ ion implanted 4H-SiC for pn junction formation, Appl. Surface Sci. 208-209 pp. 292-297 (2003).
[42] C. Boutopoulos, P. Terzis, I. Zergioti, A.G. Kontos, K. Zekentes, K. Giannakopoulos, Y.S. Raptis, Laser annealing of Al implanted silicon carbide: Structural and optical characterization”, Appl. Surf. Sci. 253 (2007), 7912–7916.
[43] K. Maruyma, H. Hanafusa, R. Ashihara, S. Hayashi, H. Murakami, and S. Higasahi, High-efficiency impurity activation by precise control of cooling rate during atmospheric pressure thermal plasma jet annealing of 4H-SiC wafer, Japan. J. Appl. Phys. 54, 06GC01 (2015).
[44] H. Hanafusa, K. Maruyma, R. Ishimaru, and S. Higasahi, High Efficiency Activation of Phosphorus Atoms in 4H-SiC by Atmospheric Pressure Thermal Plasma Jet Annealing, Mater. Sci. Forum, Vol 858, pp. 535-539, (2016).
[45] Information on
[46] Centrotherm’s private communication
[47] R. Nipoti, E. Albertazzi, M. Bianconi, R. Lotti, G. Lulli, M. Cervera and A. Carnera, “Ion implantation induced swelling in 6H-SiC”, Appl. Phys. Lett. 70 (1997) pp. 3425-3427.
[48] S. Blanqué, R.Pérez, P. Godignon, N. Mestres, E. Morvan, A. Kerlain, C. Dua, C. Brylinski, M. Zielinski and J. Camassel, Room Temperature Implantation and activation Kinetics of nitrogen and Phosphorus in 4H-SiC Crystals, Mater. Sci. Forum 457-460, pp. 893-898 (2004).
[49] K. A. Jones, P. B. Shah, K. W. Kirchner, R. T. Lareau, M. C. Wood, M. H. Ervin, R. D. Vispute, R. P. Sharma, T. Venkatesan and O. W. Holland, Annealing ion implanted SiC with an AlN cap, Mater. Sci. & Eng. Vol. B61-62, p. 281, (2000).
[50] K.V. Vassilevski, N.G. Wright, I.P. Nikitina, A.B. Horsfall, A.G. O’Neill, M.J. Uren, K.P. Hilton, A.G. Masterton, A.J. Hydes and C.M. Johnson, Protection of selectively implanted and patterned silicon carbide surfaces with graphite capping layer during post-implantation annealing, Semicond. Sci. Technol. Vol. 20, p.271 (2005).
[51] Y. Negoro, K. Katsumoto. T. Kimoto, H. Matsunami, Flat Surface after High-Temperature Annealing for Phosphorus-Ion Implanted 4H-SiC(0001) using Graphite Cap, Mater. Sci. Forum Vol. 457-460 p. 933-936 (2004).
[52] S. G. Sundaresan, M. V. Rao, Y.J. Tian, M. C. Ridgway, J. A. Schreifels, J. S. Kopanski, Ultrahigh-temperature microwave annealing of Al+- and P+-implanted 4H-SiC, J. Appl. Phys. 101, 073708 (2007).
[53] M. Rambach, A. J. Bauer, H. Ryssel, Silicon Carbide: Current trends in Research and Applications, Eds P. Friedrichs, T. Kimoto, L. Ley, G. Pensl, 2010, Wiley, p. 181
[54] M. Lazar, L. Ottaviani, M. L. Locatelli, C. Raynaud, D. Planson, E. Morvan, P. Godignon, W. Skorupa, J. P. Chante, High Electrical Activation of Aluminium and Nitrogen Implanted in 6H-SiC at Room Temperature by RF Annealing, Mater. Sci. Forum, 353-356, pp.571-574 (2001).
[55] A. Toifl, Modeling and Simulation of Thermal Annealing of Implanted GaN and SiC, B.Sc. Thesis, Technical Un. Vienna (2018).
[56] V. Šimonka, A. Toifl, A. Hössinger, S. Selberherr, J. Weinbub, Transient model for electrical activation of aluminium and phosphorus-implanted silicon carbide, J. Appl. Phys. 123 (23), 235701, (2018).
[57] V. Simonka, A. Hossinger, J. Weinbub, S. Selberherr, Empirical Model for Electrical Activation of Aluminum-and Boron-Implanted Silicon Carbide, IEEE Trans. Electron Dev. 65, 674-679, (2018).
[58] D. Goghero, F. Giannazzo, V. Raineri, P. Musumeci and L. Calcagno, Structural and electrical characterization of n+-type ion-implanted 6H-SiC, Eur. Physical J. Appl. Phys, Vol 27(1-3), pp 239-242, (2004).
[59] Y. Furukawa, H. Suzuki, S. Shimizu, N. Ohse, M. Watanabe, K. Fukuda, Distribution of Secondary Defects and Electrical Activation after Annealing of Al-Implanted SiC, Mat. Sci. Forum, Vols. 821-823, pp. 407-410, (2015).
[60] C. M. Wang, Y. Zhang, W. J. Weber, W. Jiang and L. E. Thomas, Microstructural Features of Al-Implanted 4H-SiC, J. Mater. Res., Vol. 18, pp. 772–779 (2003), and in W. J. Weber, W. Jiang, C. M. Wang, A. Hallén, and G. Possnert, Effects of implantation temperature and ion flux on damage accumulation in Al- implanted 4H-SiC, J. Appl. Phys., Vol. 93, No. 4, pp. 1954–1960 (2003).
[61] K. Kawaharaa, G. Alfieri, T. Kimoto, Detection and depth analyses of deep levels generated by ion implantation in n- and p-type 4H-SiC, J. Appl. Phys. 106, 013719 (2009).
[62] B. Zippelius, J. Suda, T. Kimoto, High temperature annealing of n-type 4H-SiC: Impact on intrinsic defects and carrier lifetime, J. Appl. Phys. 111, 033515, (2012).
[63] J. Wong-Leung, M. Janson and B. Svensson, Effect of crystal orientation on the implant profile of 60 keV Al into 4H-SiC crystals, J. Appl. Phys, Vol.93, p.8914 (2003).
[64] SILVACOTM website:
[65] E. Morvan, Modélisation de l’implantation ionique dans α-SiC et application à la conception de composants de puissance, PhD thesis, INSA Lyon (1999)
[66] E. Morvan, P. Godignon, J. Montserrat, D. Flores, X. Jorda, M. Vellvehi, Mapping of 6H-SiC for implantation control, Diam. Rel. Mat. 8, pp. 335–340 (1999).
[67] E. Morvan, P. Godignon, M. Vellvehi, A. Hallén, M. Linnarsson, and A. Yu. Kuznetsov, Channeling implantations of Al+ into 6H silicon carbide Appl. Phys. Lett. 74, 3990 (1999).
[68] A. Hallen, M. Linnarsson, L. Vines, B. Swensson, To be published in Proc. of ECSCRM2018, Birmingham (UK), September 2018.
[69] M. K. Linnarsson, A. Hallén and L. Vines, Intentional and unintentional channeling during implantation of 51V ions into 4H-SiC, Semicond. Sci. Technol. 34 (2019) 115006
[70] G. Lulli, R. Nipoti, 2D Simulation of under-Mask Penetration in 4H-SiC Implanted with Al+ Ions, Mat. Sci. Forum Vols. 679-680 pp 421-424, (2011).
[71] K. Mochizuki, N. Yokoyama, Two-Dimensional Modeling of Aluminum-Ion Implantation into 4H-SiC, Mat. Sci. Forum Vols. 679-680, pp 405-408 (2011).
[72] E. Morvan, N. Mestres, J. Pascual, D. Flores, M. Vellvehi, J. Rebollo, Mat. Sci. Eng. B61–62, 373–377 (1999).
[73] F. Torregrosa, Y. Spiegel, J. Duchaine, T. Michel, G. Borvon, L. Roux, Recent developments on PULSION® PIII tool: FinFET 3D doping, High temp implantation, III-V doping, contact and silicide improvement, & 450 mm, Proc. IWJT 2015 Kyoto.
[74] X.Y. Qian, N. W. Cheung, M. A. Lieberman, S. B. Felch, R. Brennan, and M. I. CurrentPlasma immersion ion implantation of SiF4 and BF3 for sub-100 nm Pþ/N junction fabrication, Appl. Phys. Lett. 59, 348–350, (1991).
[75] L. Ottaviani, S. Biondo, M. Kazan, O. Palais, J. Duchaine, F. Milesi, R. Daineche, B. Courtois and F. Torregrosa: Implantation of Nitrogen Atoms in 4H-SiC Epitaxial Layer: a Comparison between Standard and Plasma Immersion Processes, Adv. Mat. Res. Vol. 324, pp. 265-268, (2011).
[76] S. Biondi, M. Lazar, L. Ottaviani, W. Vervish, O. Palais, R. Daineche, D. Planson, J. Duchaine F. Milesi and F. Torregrosa: Electrical characteristics of SiC UV-Photodetector device: from the p-i-n structure behaviour to junction Barrier Schottky structure behaviour , Mat. Sci. Forum Vol. 711 pp. 114-117, (2012).
[77] M. Zielinski, S. Monnoye, H. Mank, F. Torregrosa, G. Grosset, Y. Spiegel, Novel Carbon Treatment to Create an Oriented 3C-SiC Seed on Silicon. Book of abstracts, ECSCRM 2018, August 2018.
[78] M. Robinson, I. Torrens, Computer simulation of atomic-displacement cascades in solids in the binary-collision approximation Phys. Rev. B, 9, p 5008 , (1974).
[79] O. Oen, M. Robinson, Nucl. Inst. Methods, 132 p647, (1976).
[80] E. Morvan, P. Godignon, J. Montserrat, J. Fernadez, J. Millan, J.P. Chante, Montecarlo simulation of ion implantation into SiC-6H single crystal including channeling effect, Mat. Sci. Eng. B46, pp. 218-222(1997).
[81] M.S. Janson, PhD Thesis, KTH 2003, ISSN0284-0545
[82] J. F. Ziegler, J. P. Biersack, and U. Littmark, In The Stopping and Range of Ions in Matter, volume 1, New York, Pergamon. ISBN 0-08-022053-3, (1985).
[83] W. Brandt, M. Ktitagawa, Effective stopping-power charges of swift ions in condensed matter, Physics Rev. B, 25 (9), p5631, (1982).
[84] P.M, Echenique, R.M. Niemen, J.C. Ashley and RX. Ritchie, Nonlinear stopping power of an electron gas for slow ions, Phys. Rev. A, 33, pp. 897 (1986).
[85] T. Kimoto, N. Inoue, H. Matsunami, Nitrogen Ion Implantation into α‐SiC Epitaxial Layers, Phys.Stat. Sol.(a) 162, pp. 263-276, (1997).<263::AID-PSSA263>3.0.CO;2-W
[86] J. Wong-Leung, M. K. Linnarsson, B. Svensson and D. J. H. Cockayne, Ion-implantation-induced extended defect formation in (0001) and (11-20) 4H-SiC, Phys. Rev. B 71, 165210 2005.
[87] K. Zekentes, K. Tsagaraki, A. Breza and N. Frangis, The formation of new periodicities after N-implantation in 4H- and 6H- SiC samples, Mat. Sci. Forum Vols. 740-742 pp 447-450 (2013).
[88] J. Camassel, S. Blanque, N. Mestres, P. Godignon and J. Pascual, Comparative evaluation of implantation damage produced by N and P ions in 6H‐SiC, Phys. Stat. Sol. A, 195, p.875- 880 (2003).
[89] K.B. Mulpuri, S.B. Qadri, J. Grun, C.K. Manka and M.C. Ridgway, Annealing of ion-implanted SiC by laser-pulse-exposure-generated shock-waves, Solid-State Electronics 50, pp.1035–1040, (2006).
[90] Z.C. Feng, S.C. Lien, J.H. Zhao, X.W. Sun and W. Lu, Structural and Optical Studies on Ion-implanted 6H–SiC Thin Films, Thin Solid Films 516, pp.5217–5222 (2008).
[91] K. Zekentes, K. Tsagaraki, M. Androulidaki, M. Kayambaki, A. Stavrinidis, H. Peyre and J. Camassel, Room temperature physical characterization of implanted 4H- and 6H-SiC, Mat. Sci. Forum. 717-720 pp 589-592 (2012).
[92] M. Buzzo, M. Ciappa, J. Millan, P. Godignon, W. Fichtner, Microelectronic Engineering 84 pp. 413–418 (2007).
[93] R. Elpelt, B. Zippelius, S. Doering, U. Winkler, Employing Scanning Spreading Resistance Microscopy (SSRM) for Improving TCAD Simulation Accuracy of Silicon Carbide, Mater. Sci. Forum, 897, p295, (2017).
[94] F. Giannazzo, L. Calcagno, F. Roccaforte, P. Musumeci, F. LaVia, V. Raineri, Dopant profile measurements in ion implanted 6H–SiC by scanning capacitance microscopy, Appl. Surface Sci. 184(1-4), 183 (2001).
[95] O. Ishiyama, S. Inazato, Dopant Profiling on 4H Silicon Carbide P+N Junction by Scanning Probe and Secondary Electron Microscopy, J. Surface Analysis 14(4), pp. 441-443 (2008).
[96] K. Tsagaraki, M. Nafouti, H. Peyré, K. Vamvoukakis, N. Makris, M. Kayambaki, A. Stavrinidis, G. Konstantinidis, M. Panagopoulou, D. Alquier, K. Zekentes, Cross-section doping topography of 4H-SiC VJFETs by various techniques, Mat. Sci. Forum. 924, pp. 653-656, (2018).
[97] J. Suda, S. Nakamura, M. Miura, T. Kimoto and H. Matsunami, Scanning Capacitance and Spreading Resistance Microscopy of SiC Multiple-pn-Junction Structure, Jpn. J. Appl. Phys., 41, L40 (2002).