Effects of interface state charges on the electrical properties of Si/SiC heterojunctions

Electrical properties of p−-Si/n−-SiC, p-Si/n−-SiC, p+-Si/n−-SiC, and n+-Si/n−-SiC heterojunctions fabricated by using surface-activated bonding are investigated. Their flat-band voltages obtained from capacitance-voltage (C-V) measurements are found to be ∼0.92 eV, which suggests that the Fermi level should be pinned at the bonding interface. An analysis by using the charge neutral level model reveals that the C-V characteristics are sensitive to the density of interface states. The measured C-V characteristics of p+-Si/n−-SiC and n+-Si/n−-SiC junctions are in quantitative agreement with modeled ones obtained for the interface states density and the conduction-band discontinuity of 2.3 × 1013 cm−2 eV−1 and 0.3 eV, respectively.