Characterization of energy levels related to impurities in epitaxial 4H-SiC ion implanted p~+n junctions

摘要

The distribution of energy levels within the bandgap of epitaxial 4H-SiC p~+ junctions was studied. The junction was obtained by Al ion implantation on a nitrogen doped n-type epitaxial substrate. Thermally stimulated currents/capacitance (TSC/TSCAP) as well as current/ capacitance deep level transient spectroscopy (I- and C-DLTS) were carried out over a wide temperature range (20-400 K). The two TSC/DLTS peaks associated with N-doping were detected for the first time and their trap signatures determined. Two hole traps relating to deep and shallow boron confirm that a boron contamination occurred during crystal growth. A negligible concentration of the Z_(1/2) level, which is usually the dominant level produced by irradiation of ion implant, was measured. The concentrations of all observed traps were significantly lower than nitrogen one, which determines the doping. This evidence supports the high quality of the processed junctions, making these devices particularly attractive for future use in particle detection as well as in optoelectronic applications.