Crystalline Defects in β-SiC as Revealed by a NaOH-KOH Eutectic Etch

Abstract

Antiphase boundaries (APBs), stacking faults and dislocations in 3-silicon carbide are revealed by etching with the KOH-NaOH eutectic at 350°C. Within the region enclosed by an APB, the orientation of features attributed to stacking faults and to dislocations is uniform. The orientation is rotated by 90° on opposite sides of the APB. With β-SiC grown epitaxtally on silicon substrates (using silane and propane in a hydrogen ambient), we have used the eutectic etch to study the effect of growth variables on the crystalline quality. APBs appear to decrease in number with increasing layer thickness and with increasing [C]/[Si] (at constant ([C] + [Si])) in the process gas mixture. β-SiC layers grown on off-axis (100) silicon have a dramatically reduced incidence of APBs, although they are not entirely free of them. We will discuss details of these and other studies of the crystalline quality of β-SiC that we have made with the eutectic etch.