Overgrowth of Protrusion Defects during Sublimation Growth of Cubic Silicon Carbide Using Free-Standing Cubic Silicon Carbide Substrates
We investigated the overgrowth of protrusion defects during sublimation growth of cubic silicon carbide (3C-SiC) using free-standing on-axis and off-axis substrates. Three different overgrowth mechanisms were found to contribute to defect elimination: (i) mutual overgrowth by defects of the same type, (ii) real overgrowth by step-flow growth, and (iii) overgrowth by quasi-step-flow growth at surface irregularities. Mechanisms (i) and (iii) are not real overgrowth mechanisms because they are directly linked to the inducing defects themselves or other undesired disturbances of the substrate. However, at high defect densities or for the on-axis substrate, they represent a relevant elimination mechanism. Overgrowth according to (ii) is possible only for off-axis substrates and represents a real elimination mechanism, leading to an improvement of the material quality. In the context of this work, we provide a phenomenological description of the overgrowth principle as well as limitations for the defect elimination, depending on the structure of the protrusions. For the first time, the overgrowth of protrusions has been categorized for different types and qualities of substrates. Fundamental differences were identified, which can lead to a more focused further development of defect elimination in 3C-SiC.