Influence of the growth interface shape on the defect characteristics in the facet region of 4H-SiC single crystals

TL;DR

This study investigates how the shape of the growth interface in 4H-SiC single crystals affects defect formation, revealing that interface shape influences micropipe deflection and dislocation reduction during crystal growth.

Contribution

It demonstrates the impact of radial temperature gradients on the growth interface shape and defect characteristics in 4H-SiC crystals using in-situ CT monitoring.

Findings

Larger radial temperature gradient results in steeper crystal flanks.

Steeper flanks cause micropipes to deflect laterally.

Dislocation density reduces by 60% with certain interface shapes.

Abstract

Two 75mm 4H-SiC single crystals are grown by the physical vapor transport (PVT) technique, using different insulation materials. The insulation material of higher thermal conductivity led to an increased radial temperature gradient. The evolution of the growth front was monitored using the in-situ computed tomography (CT). A slightly bent growth interface and a bigger facet are formed during the growth applying a lower radial temperature gradient while a smaller facet and steeper crystal flanks are formed in the case of the larger radial temperature gradient. Micropipes are deflected laterally by large surface steps on the steep crystal flanks and a reduction of threading edge dislocations by 60% is revealed by KOH defect etching.