Polytype controlled SiC epitaxy on on-axis 6H-SiC(0001) by adding HCl during growth

Abstract

The homoepitaxial growth of 6H-SiC is demonstrated on on-axis 6H-SiC(0001) substrates at 1475 °C by adding HCl during the growth by chemical vapor deposition. In prior studies, a pregrowth stepped surface obtained either by several-degree off-cut substrates or a HCl pregrowth etch was required to suppress 3C-SiC inclusions and to achieve homoepitaxial growth of 6H-SiC. In contrast, the addition of HCl during the growth decorates the grown surface via etching to provide an in situ stepped surface where step-flow growth of 6H-SiC occurs. Atomic force microscopy of the deposited films shows the addition of HCl produces a much more regular step and terrace structure that is characteristic of near equilibrium, step-flow growth. In addition, HCl can reduce the surface supersaturation and growth rate, remove the undesired nucleation sites for 3C-SiC, and etch 3C-SiC inclusions over 6H-SiC, all of which benefit the homoepitaxial growth of 6H-SiC on on-axis substrates.