Using our own substrate growth and epitaxial growth techniques, we fabricated a 1.4 kV mesa-type 6H-SiC pn diode with an ideal avalanche breakdown and without forward degradation. The 6H-SiC substrates were grown on Lely crystals with no micropipes and only minimal defects. A pn junction was fabricated. by chemical vapor deposition (CVD) with p(+)/n(-) epitaxial films. We obtained 1.4 kV breakdown voltage, consistent with the ideal breakdown voltage calculated from the thickness (10mum) and doping concentration (2x10(16)cm(-3)) of the drift layer. The application of 200 A/cm(2) current stress in the forward direction produced no degradation, which is often observed with pn diodes on normal commercial substrates.