In this paper we report on the fabrication of large area 4H-SiC Schottky diodes based on SiC substrate materials with reduced defect density. Several techniques improving material quality including micropipe filling technique and porous SiC fabrication technique were used to reduce defect density in device structures. Open micropipes were not found in SiC wafers after micropipe filling procedure. X-ray diffraction measurements showed substantial material quality improvement. Low doped device layers were grown by CVD on 4H-SiC substrates with reduced defect density. Schottky diodes with various areas were fabricated on these CVD grown layers. Record size 1x1 cm(2) area diode with blocking voltage of 300 V and low leakage current was demonstrated. Smaller size diode chips (0.03 cm(2)) with 600 V blocking voltage were packaged providing devices with on-state resistance as low as 0.004 Omegaxcm(2) and forward voltage drop as low as 1.9 V at 8 A current (>260 Axcm(-2)).