Photoelectrical characterization of heavily doped p-SiC Schottky contacts

Abstract

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 × 10¹⁸ to 5 × 10¹⁹ cm⁻³. Although the current–voltage (I–V) characteristics had lost rectification, reasonable Schottky barrier height (qϕ _B) values were obtained up to 1 × 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 qϕ _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 qϕ _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.