Effect of Bulk Potential Engineering on the Transport Properties of SiC MOSFETs: Characterization and Interpretation V. Uhnevionak, 1,5,a* A. Burenkov, 1,5 C. Strenger, 1,5 G. Ortiz, 3,5 V. Mortet, 4,5 E. Bedel-Pereira, 3,5 F. Cristiano, 3,5 A. J. Bauer, 1,5 P. Pichler 1,2,5 1 Fraunhofer IISB, Schottkystrasse 10, 91058 Erlangen, Germany 2 Chair of Electron Devices, Cauerstrasse 6, 91058 Erlangen, Germany 3 CNRS-LAAS, 7 avenue du colonel Roche, 31400 Toulouse, France 4 Institute of Physics, Academy of Sciences of the Czech Republic, v.v.i, Prague 8, Czech Republic 5 The Wide Bandgap Semiconductor Alliance (WISEA) a viktoryia.uhnevionak@iisb.fraunhofer.de Keywords: 4H-SiC MOSFETs, interface traps, bulk traps, depth dependence. Abstract. The effect of bulk potential engineering on the transport properties in the channel of SiC MOSFETs has been studied. For this purpose, n-channel SiC MOSFETs have been manufactured with different background doping concentrations and characterized electrically at room temperature by current-voltage as well as by Hall-effect measurements. To interpret the measurements performed, numerical simulations have been carried out using Sentaurus Device of Synopsys. The main finding of the simulation analysis is that the change in the depth of the band-bending has to be considered to explain the doping dependence of SiC MOSFET characteristics. Introduction Because of its unique physical and electronic properties, silicon carbide has become a promising material for the development of field-effect transistors for high-power electronics. However, due to the low drain current and mobility in the channel, the commercial use of SiC-based MOSFETs is still limited. Their low performance is mainly explained by the high density of charged traps at the SiO 2 /SiC interface which results in strong Coulomb scattering. To increase the channel mobility, the impact of Coulomb scattering at the charged interface traps has to be reduced. Currently, the main strategy for a reduction of the aforementioned scattering mechanism is based on methodologies for the passivation of the interface traps. However, it is important to note that the intensity of Coulomb scattering doesn’t depend on the amount of traps by itself but on the amount of traps which are occupied and charged. The lower the amount of the charged interface traps, the lower the intensity of Coulomb scattering and the higher the channel mobility. In addition to the passivation methodologies, the amount of charged interface traps which affect the performance of MOSFETs can be controlled by changing the background doping concentration N A . A change in the background doping concentration corresponds to a change in the bulk potential  B . By changing the bulk potential and, as a consequence, the band-bending required to invert the MOSFET channel, the occupation of the traps located at the interface also changes. Along that line, it has been suggested that a reduction of the background doping concentration leads to a reduction of the density of charged interface traps and with them of Coulomb scattering [1, 2]. The reduced density of charged interface traps was then taken as an explanation for the mobility increase in lateral SiC MOSFETs found experimentally. However, it was found in the current work that an explanation of the increased channel mobility requires a broader view of the effects associated with a decreasing N A . Experiments To study the effect of bulk potential engineering, lateral n-channel 4H-SiC MOSFETs have been fabricated on p-type 4°-off 4H-SiC (0001) Si-face substrates with aluminum concentrations N A of 1·10 15 cm -3 , 1·10 16 cm -3 , and 5·10 16 cm -3 . The channel length and width of the MOSFETs were Materials Science Forum Vols. 821-823 (2015) pp 737-740 Submitted: 2014-09-03 © (2015) Trans Tech Publications, Switzerland Revised: 2014-11-25 doi:10.4028/www.scientific.net/MSF.821-823.737 Accepted: 2015-01-21 Online: 2015-06-30 All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans Tech Publications, www.ttp.net. (ID: 140.93.4.102, University of Toulouse, Toulouse, France-06/07/15,15:38:44)