Improvements in the Reverse Characteristics of 4H-SiC Schottky Barrier Diodes by Hydrogen Treatments

Abstract

We fabricated 4H-SiC Schottky barrier diodes with various metals such as titanium, nickel and platinum. Density of interface states D it and neutral level φ o (which is the position that the Fermi level must assume if the surface is electrically neutral) were calculated 1.8×1012 cm -2 eV -1 and 1.76 eV, respectively. In order to reduce reverse leakage current, hydrogen annealing and hydrogen plasma treatment were performed after Schottky contact metallization. The reverse leakage current measured at -100 V was reduced by one or two order of magnitude. An improvement of reverse leakage current was observed in case of both hydrogen annealing and hydrogen plasma treatment.

Electrical Characterizations of Hydrogenated 4H-SiC Epitaxial Samples

“…A little increase of Φ b , extrapolated at 0 K, is found to outcome from the annealing : 0.79 eV is calculated for the virgin sample, and 0.82 eV for the annealed one. For temperatures higher than 320 K, the barrier heights of the annealed samples become slightly lower than those of the virgin ones : Φ b (annealed) = 1.50 eV and Φ b (virgin) = 1.56 eV at 500 K. Kim et al also observed a little decrease of Φ b for Ni/4H-SiC Schottky contacts after annealing under H 2 [4]. This indicates that interface state density between the metal and semiconductor is not really affected by hydrogenation, which effects may be more important in the sub-surface epitaxial layer.…”

Schottky Barrier Diode Fabricated by MOCVD-Grown Epilayer Using Bis-Trimethylsilylmethane Precursor

“…Ohmic contacts, annealed NiSi x , were deposited on the back surface of substrates. For the enhancement of breakdown voltage, field-plate edge termination technique [3] was used. For a small contact resistance during the electrical measurement of SBD, gold pad metal was deposited on the Schottky metal layer.…”