Photoelectrochemical capacitance-voltage measurements of 4H-SiC

Photoelectrochemical capacitance-voltage (PC-V) measurements have been successfully made on 4H-SiC material. The 0.05 M KOH solution used as a Schottky contact etches the material with an average roughness of about one percent of the total average etch depth at an etch rate of 1 μm/h. This capability allows the carrier concentration profile of thicker layers with different doping levels to be analyzed. The PC-V measurements are compared with secondary ion mass spectroscopy. The results show agreement with nitrogen doping in the top epitaxial layer and in the substrate. The PC-V measurement also sees an unknown species diffusing out of the substrate into the nominally undoped buffer layer.