Influence of Morphological Changes in a Source Material on the Growth Interface of 4H-SiC Single Crystals

• Main Authors: Matthias Arzig, Johannes Steiner, Michael Salamon, Norman Uhlmann, Peter J. Wellmann
• Format: Article
• Language: English
• Published: MDPI AG 2019-08-01
• Series: Materials
• Subjects: in-situ CT; Laser flash; thermal conductivity; source material; numerical modelling; Computer Tomography; supersaturation; growth kinetics
• Online Access: https://www.mdpi.com/1996-1944/12/16/2591

In this study, the change of mass distribution in a source material is tracked using an in situ computer tomography (CT) setup during the bulk growth of 4H- silicon carbide (SiC) via physical vapor depostion (PVT). The changing properties of the source material due to recrystallization and densification are evaluated. Laser flash measurement showed that the thermal properties of different regions of the source material change significantly before and after the growth run. The Si-depleted area at the bottom of the crucible is thermally insulating, while the residual SiC source showed increased thermal conductivity compared to the initially charged powder. Ex situ CT measurements revealed a needle-like structure with elongated pores causing anisotropic behavior for the heat conductivity. Models to assess the thermal conductivity are applied in order to calculate the changes in the temperature field in the crucible and the changes in growth kinetics are discussed.