Vapor–liquid–solid growth of 4H-SiC single crystal films with extremely low carrier densities in chemical vapor deposition with a Pt–Si alloy flux and X-ray topography analysis of their dislocation propagation behaviors

Abstract

A vapor–liquid–solid (VLS) mechanism has been successfully applied to homoepitaxial growth of 4H-SiC films in chemical vapor deposition (CVD), to which the key is the use of a Si–Pt alloy flux in the CVD–VLS process. The n-type residual carrier density in the VLS-grown SiC films could be reduced down to the order of 10¹⁵ cm⁻³ despite possible concern about impurities working as dopants incorporated into VLS-grown films. The surface morphology essentially exhibited a bunched step-and-terrace structure, as similarly observed in solution-grown SiC crystals. Furthermore, the dislocation propagation behaviors, investigated by X-ray topography analysis, were also rather similar in solution growth processes, but different from those in conventional CVD processes. That is, threading dislocations can be converted to basal plane dislocations in their propagation in the CVD–VLS process, illustrating its potential to effectively reduce the total dislocation density in the resultant SiC thick films.