Correlation between the electrical properties of p-Si/n-4H-SiC junctions and concentrations of acceptors in Si

Abstract

We fabricated p+-, p-, and p−-Si/n-4H-SiC junctions by surface activated bonding (SAB). We investigated their electrical properties by measuring their current–voltage (I–V) characteristics at raised ambient temperatures, capacitance–voltage (C–V) characteristics at various frequencies, and capacitance–frequency (C–f) characteristics at room temperature. The activation energy of their reverse-bias current and the flat-band voltage in their C–V characteristics, which were estimated to be 0.97–1.01 eV and 0.83–0.84 V, respectively, were insensitive to the concentrations of acceptors in Si substrates. The relaxation times estimated from the C–f characteristics were 0.8 and 1.5 µs for the p-Si/n-4H-SiC and p−-Si/n-4H-SiC junctions, respectively. The results are explained by a scheme wherein Fermi level pinning occurs at the Si/4H-SiC interfaces fabricated by SAB.