High Power 4H-SiC PiN Diodes with Minimal Forward Voltage Drift

Rapid advancement has been shown for 4H-SiC PiN diodes. High quality epitaxial drift layers as thick as 200 mum (17.3 kV breakdown voltage) have been grown for PiN structures having a forward voltage drop (VF, at 100 A/cm2) as low as 6.3 V for 3 mm diameter devices. As impressive as these results are, 4H-SiC PiN diodes continue to suffer from forward voltage instability. Recently, great strides have been made in 4H-SiC epitaxy to produce relatively drift-free PiN structures. Large area power devices capable of handling up to 7.5 A of current and blocking 10 kV have been fabricated on this state of the art epitaxy. To maximize the breakdown voltage, a three zone Junction Termination Extension (JTE) was formed via boron ion implantation. Low resistance (approx 10-7 Omega-cm2) contacts to p-type 4H-SiC, high carrier lifetime (approx 1 musec) and improved injection efficiency of the epitaxial material enable a record low VF of 3.74 V on a 100 mum drift layer. More importantly, 20% of the yielded large area parts (0.05 cm2 and 0.075 cm2) exhibit a high degree of forward voltage stability.