Abstract
Profit from high current gain features, 4H-SiC power Darlington transistor has the capacity for handling high current transmission. In this paper, monolithic Darlington transistors were fabricated using a simultaneous formation process for both n-type (emitter) and p-type (base) ohmic contact. The isolated device shows current gain of 1061 and 823 with collector current density (JC) increasing from 200 to 800 A/cm2, exhibiting a slight current gain drop at high JC. By extracting the interface state density (Dit) between SiO2 and p-type 4H-SiC, it is found that this advantage owes to the improvement of the shallow bulk minority carrier lifetime in base region. Furthermore, ISE-TCAD (technology computer aided design) simulation was carried out to study the relationship between base minority lifetime and the current gain, from which the total base minority lifetime is estimated to be 48 ns. The open base breakdown voltage (BVCEO) is 850 V at a leakage current of 2 μA due to the electric filed crowding at the isolation bottom between drive bipolar junction transistor (BJT) and output BJT. To solve this, non-isolated devices were also fabricated with improved BVCEO of 2370 V, indicating the superior potential of 4H-SiC monolithic Darlington transistors for high power application, while the current gain is deceased to 420, which needs further improvement.
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References
She X, Huang A Q, Lucia O, et al. Review of silicon carbide power devices and their applications. IEEE Trans Ind Electron, 2017, 64: 8193–8205
Song Q W, Yuan H, Han C, et al. Fabrication of a monolithic 4H-SiC junction barrier schottky diode with the capability of high current. Sci China Tech Sci, 2015, 58: 1369–1374
Song Q W, Zhang Y M, Zhang Y M, et al. 4H-SiC trench gate MOSFETs with field plate termination. Sci China Tech Sci, 2014, 57: 2044–2049
Liu G, Tuttle B R, Dhar S. Silicon carbide: A unique platform for metal-oxide-semiconductor physics. Appl Phys Rev, 2015, 2: 021307
Calderon-Lopez G, Forsyth A J, Gordon D L, et al. Evaluation of SiC BJTs for high-power DC-DC converters. IEEE Trans Power Electron, 2014, 29: 2474–2481
Tang Y, Chow T P. Demonstration of monolithic darlington transistors in 4H-SiC. Mater Sci Forum, 2003, 433-436: 789–792
Tang Y, Chow T P. Monolithic 4H-SiC Darlington transistors with a peak current gain of 2000. In: IEEE Device Research Conference. Salt Lake City, 2003. 79–80
Zhang J, Li X, Alexandrov P, et al. Fabrication and characterization of high-current-gain 4H-SiC bipolar junction transistors. IEEE Trans Electron Devices, 2008, 55: 1899–1906
Ghandi R, Buono B, Domeij M, et al. High current-gain implantationfree 4H-SiC monolithic darlington transistor. IEEE Electron Device Lett, 2011, 32: 188–190
Webster W. On the variation of junction-transistor current-amplification factor with emitter current. Proc IRE, 1954, 42: 914–920
Yuan L, Song Q, Tang X, et al. Influence of base carrier lifetime on the characteristics of 4H-SiC BJTs. Superlattices Microstruct, 2017, 102: 127–133
Buono B, Ghandi R, Domeij M, et al. Modeling and characterization of current gain versus temperature in 4H-SiC power BJTs. IEEE Trans Electron Devices, 2010, 57: 704–711
Miyake H, Kimoto T, Suda J. 4H-SiC BJTs with record current gains of 257 on (0001) and 335 on (000-1). IEEE Electron Device Lett, 2011, 32: 841–843
Okuda T, Kimoto T, Suda J. Improvement of carrier lifetimes in highly Al-doped p-type 4H-SiC epitaxial layers by hydrogen passivation. Appl Phys Express, 2013, 6: 121301
Ivanov P A, Levinshtein M E, Rumyantsev S L, et al. Factors limiting the current gain in high-voltage 4H-SiC npn-BJTs. Solid-State Electron, 2002, 46: 567–572
Kawahara K, Suda J, Kimoto T. Analytical model for reduction of deep levels in SiC by thermal oxidation. J Appl Phys, 2012, 111: 053710
Schroder D K. Semiconductor Material and Device Characterization. 3rd Ed. New York: Wiley, 2006
Yuan L, Song Q, Tang X, et al. Geometrical effects in JTE rings termination for 4H-SiC medium-voltage devices. Semicond Sci Technol, 2017, 32: 125015
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Yuan, L., Song, Q., Tang, X. et al. 4H-SiC monolithic Darlington transistors with slight current gain drop at high collector current density. Sci. China Technol. Sci. 61, 1238–1243 (2018). https://doi.org/10.1007/s11431-017-9208-4
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DOI: https://doi.org/10.1007/s11431-017-9208-4