Influence of 4H-SiC semi-insulating substrate purity on SiC metal-semiconductor field-effect transistor performance

The performances of silicon carbide (SiC) metal-semiconductor field-effect transistors (MESFETs) fabricated on conventional V-doped semi-insulating substrates and new V-free semi-insulating substrates have been compared. The V-free 4H-SiC substrates were confirmed by secondary ion mass spectrometry (SIMS). X-ray topography revealed significantly fewer micropipes and low-angle boundaries in V-free semi-insulating substrates than in conventional V-compensated substrates. Deep-level transient spectroscopy (DLTS) indicated that the spectra signals observed in conventional V-doped substrates were either reduced or disappeared in V-free substrates. The intrinsic deep levels in V-free substrates to make semi-insulating properties were also observed in DLTS spectra. Under various DC and RF stresses, SiC MESFETs fabricated on new V-free semi-insulating substrates showed superior device performance and stability.