Low loss, large area 4.5 kV 4H-SiC PIN diodes with reduced forward voltage drift

摘要

4H-SiC PIN diodes have been fabricated on a Norstel P~+/N/N~+ substrate with a combination of Mesa and JTE as edge termination. A breakdown voltage of 4.5 kV has been measured at 1 μA for devices with an active area of 2.6 mm~2. The differential on-resistance at 15 A (600 A cm~(-2)) was of only 1.7 mΩ cm~2 (25 ℃) and 1.9 mΩ cm2 at 300 ℃. The reduced recovery charge was of 300 nC for a switched current of 15 A (500 V) at 300 ℃. 20% of the diodes showed no degradation at all after 60 h of dc stress (25-225 ℃). Other 30% of the diodes exhibit a reduced voltage shift below 1 V. For those diodes, the leakage current remains unaffected after the dc stress. Electroluminescence investigations reveal a very low density of stacking faults after the dc stress. The manufacturing yield evidences the efficiency of the substrate surface preparation and our technological process.