Photoelectrical characterization of heavily doped p-SiC Schottky contacts

The availability of photoelectrical characterizations of heavily Al-doped p-SiC Schottky contacts was clarified. We conducted a systematic study of four samples with different Al doping concentrations from 1 x 1018 to 5 x 1019 cm-3. Although the current-voltage (I-V) characteristics had lost rectification, reasonable Schottky barrier height (q phi B) values were obtained up to 1 x 1019 cm-3 by capacitance voltage, photo response, and scanning internal photoemission microscopy (SIPM) measurements. In the two-dimensional characterization by SIPM, large photocurrent spots corresponding with low q phi B were observed in an average density of 103 to 104 cm-2. However, except for these spots, a high uniformity of about 2 meV standard deviation was obtained for q phi B over the entire observed electrodes. These results indicate that SIPM is able to characterize the inhomogeneity of heavily doped p-SiC contacts with very leaky I-V characteristics.