EFFECT OF THE JUNCTION INTERFACE PROPERTIES ON BLUE EMISSION OF SIC BLUE LEDS GROWN BY STEP-CONTROLLED CVD

6H-SiC blue LEDs were successively fabricated on off-axis (0001) substrates by step-controlled CVD at 1500-degrees-C using SiH4 and C3H8. LEDs on the (0001)Si face showed dominantly a pure-blue 455 nm peak corresponding to the cathodoluminescence (CL) of the p-layer, while those on the (0001BAR)C face showed mainly a purple-blue 425 nm peak corresponding to the CL of the n-layer. Considering the carrier concentrations of the LEDs, electrons are expected to be injected into the p-layer and to recombine with holes in the p-layer. The effect of a thin interface layer between the n-layer and the p-layer is supposed for the (0001BAR)C face, but the effect disappeared by continuous electrical driving of the LEDs and the spectra became similar to those for the (0001)Si face. Atomic disorder of the SiC layer and/or doped impurities at the junction interface probably cause the interface layer.