The etching behaviour of dislocations in N-doped 4H-SiC substrate

Abstract

The substrate-induced dislocations in the homo-epitaxial film could affect the quality of the epitaxial layer and lead to degradation of the device performance and stability. Effective evaluation of dislocations in 4H-SiC substrate is crucial for the quality control of the material. This work reported the etching behaviours of threading screw dislocation (TSD), threading edge dislocation (TED), and basal plane dislocation (BPD) in 4H-SiC substrate. Potassium hydroxide (KOH) and sodium peroxide (Na2O2) with different mass ratios were used as etchants. It was found that the average size of etching pits for each kind of dislocation increased linearly with the increase in the mass ratios of Na2O2. Interestingly, the slope of the linear increase for TSD was significantly larger than that of TED or BPD, which implies that the etching behaviour of TSD is more sensitive to the oxidant content in etchants, compared to TED and BPD. This outcome is related to the larger Burgers vector in TSD. In addition, the slope of TED was nearly equal to that of BPD due to the same Burgers vectors in them. The results in the work are helpful for understanding the etching mechanism and improving the etching technology for 4H-SiC substrate and epitaxial film.