Investigation of Basal Plane Dislocation Reduction/Elimination by Molten KOH-NaOH Eutectic Etching Method

Abstract

An optimized molten KOH-NaOH eutectic etching method is developed to reveal defects in highly n-doped SiC substrates and to pre-treat the substrate prior to epitaxial growth. Different from the conventional KOH etching method, by way of eutectic method, the basal plane dislocation (BPD) conversion in the subsequent epitaxial growth is independent of the etch pit size pre-generated on the substrate. Even with a short period (~3 minutes) of pretreatment which does not generate any visible etch pits or degradation of surface morphology on the substrate, an epilayer with low BPD density -2 is still achieved. This simple and non-destructive method shows high potential to be practically employed as one of the basic pretreatment steps to the substrates in SiC epitaxial growth in order to achieve very low or free BPD density.