SiC blue LEDs were fabricated by the dipping technique, using 6H-SiC substrates whose (0001̄)C face varied toward the [112̄0] or [101̄0] direction. The surface morphology of the epitaxial layers on the off-oriented substrates was a striped pattern perpendicular to the off-axis direction. By using off-oriented substrates, the degradation of SiC blue LEDs can be greatly reduced. High-efficiency blue LEDs (12 mcd at 20 mA) were fabricated by increasing the amount of Al dopant in the n-type layer.

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ABSTRACT4H-SiC single crystals have been fabricated on the seeds of 6H-type crystals by the vacuum-sublimation (modified Lely) method at a temperature of 2400 °C and under a pressure of 2–60 mbar in an argon atmosphere. Liquid phase epitaxy was attempted by using a dipping method with a 4H-SiC off-orientation substrate whose {0001} C-face varied toward the <1120> direction by 5 degrees. The polytype of the grown crystals was found to be the 4H-type through measurements of Raman scattering and photoluminescence. P-n junction diodes were epitaxially obtained on 4H-SiC substrates. Aluminum and nitrogen were doped as acceptors and donors, respectively. The LED emitted bluish-purple light with a high brightness of 2.2 mcd at a forward current of 20 mA. Other characteristics were as follows : 420–425 nm peak wavelength, 90 % color purity, and a light output of 4 μW.

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