Low-temperature homoepitaxial growth of α-SiC on on-axis (0 0 0 1) substrate by vapor–liquid–solid mechanism

Abstract

Vapor–liquid–solid mechanism was used for growing epitaxial SiC layers on on-axis 6H–SiC and 4H–SiC substrates. By feeding Al 70Si 30 melts with propane, homoepitaxial growth was demonstrated on both polytypes down to 1100 °C, which is the lowest temperature ever reported for growing homoepitaxial layers on low tilt angle SiC substrates. However, at this temperature, the surface morphology is rough and non-uniform with spiral growth, forming large hillocks at the places where screw dislocation emerges from the substrate. Raman spectroscopy confirms the absence of 3C–SiC polytype and shows the high Al doping of the layers. Increasing temperature to 1200 °C eliminates these hillocks but creates other morphological features due to fast substrate etching at this high temperature before growth starts. These defects were reduced in size by introducing propane at 1100 °C before ramping to 1200 °C and completely eliminated by increasing the Si content of the melt to 50 at%.