Prior to deposition, the 4H-SiC wafers were sawed into 10 × 10 mm 2 pieces. The orientations of the 4H-SiC substrates used were 4H-SiC(0001) and 4H-SiC(0001 ̅ ) which conventionally refers to the Siterminated and C-terminated sides, respectively. The offcut relative to the c-axis was +/-0.5° (commonly referred as on-axis). Prior to deposition, the substrates were degreased in acetone for five minutes followed by ethanol for five minutes, both using an ultrasonic bath. This cleaning step was followed by a standard cleaning procedure for semiconductors with etching in oxidating alkaline solution (ammonia solution (25 %), hydrogen peroxide solution (48 %) and water in respective proportions 1:1:5) at 80 °C for five minutes followed by rinse in deionized water and further treatment in hot oxidizing acidic solution (hydrochloric acid solution (37 %), hydrogen peroxide (48 %) and water in respective proportions 1:1:6) at 80 °C for five minutes and finally rinse in deionized water.