Epitaxial Growth on 4H-SiC on-Axis, 0.5°, 1.25°, 2°, 4°, 8° Off-Axis Substrates – Defects Analysis and Reduction

Abstract

A good selection of growth parameters (in-situ etching, C/Si ratio, growth rate) enables obtaining of ~1nm high steps of epitaxial layers, which are comparable to the size of an elementary cell (8°off-axis) and achieve the density of BPD=8•103/cm2. Due to crystallization on substrates with low misorientation (<2°off-axis) it is possible to obtain epitaxial layers substantially lacking in BPD dislocations. However, a slightly more developed surface with Ra=1-2.5nm (1.25°, 2°off-axis) characterizes these layers. By lowering the C/Si ratio, morphology of layers crystallized on substrates with low misorientation was improved. Extending growth rate improved both the crystallographic quality of the grown layers and their polytype stability. Nevertheless, growth without BPDs, also referred to as the homogeneous (4H) polytypic growth on 4H-SiC on-axis substrates, is the most efficient way of defect elimination.