6 kV GaN p–n diode fabricated by hybrid epitaxial growth with regrowth interface treated by CF4 plasma

A high breakdown voltage was achieved for a p–n junction diode grown by a hybrid epitaxial growth. Using a quartz-free hydride vapor-phase epitaxy, a thick and extremely high-purity n−-GaN drift layer was grown on a GaN substrate. A p-GaN layer was grown on the n−-GaN drift layer using metal-organic vapor-phase epitaxy (MOVPE). Before the MOVPE growth, inductively coupled plasma dry etching treatment using CF4 gas was performed on the regrowth surface to reduce the effect of Si contamination. The device with a reduced effective donor sheet concentration at the regrowth interface obtained by the CF4 treatment achieved a high breakdown voltage of 6.23 kV with good diode characteristics. A clear correlation was found between the breakdown voltage and the effective donor concentration at the p–n junction determined by C–V measurements. It is predicted that a breakdown voltage as high as 8 kV can be obtained if the effective donor concentration at the p–n junction is reduced to 1 × 1012 cm−2 or lower.