Papers by Author: Guoli L. Sun

Abstract: We present the results of an optical investigation performed using low temperature photomuminescence and Raman spectroscopy on bulk 3C-SiC samples grown with the Continuous-Feed Physical Vapor Transport technique, using a small diameter neck to filter the defects and improve the as-grown material.

Abstract: This work presents the crystalline quality investigation of 3C-SiC unseeded crystals grown from vapor phase. Samples were polished after different crystallographic planes from crystals grown with or without nitrogen flow. The structural and optical investigation showed that the central part of the samples exhibited a very good crystalline quality. The best samples proved to be the {100} growth sectors where the only defects found were stacking faults with a defect density under 103 cm-1. At the edges, i.e. between two adjacent growth sectors, structural investigation by transmission electron microscopy revealed stacking faults and hexagonal polytype inclusions. The nitrogen doping was found not to have an influence on the crystalline quality.

Abstract: The Continuous Feed-Physical Vapor Transport Technique (CF-PVT) was optimized by considering the heating, thermal insulation and the geometry of growth cavity. The effects of seeds on the surface morphology of the grown layer have been discussed. We successfully grew 3C-SiC bulk with a diameter of 7.0 mm and 3.3 mm in height with a high growth rate of 0.8 mm/h by the CF-PVT technique.

Abstract: The control of the nucleation step is a critical issue for a future development of 3C-SiC bulk growth. The possibility to get very high quality 3C-SiC single crystal through self-nucleation on graphite was already demonstrated but the large number of nuclei limits the growth of only one crystal. In this study, we have investigated different configurations that help improving the nucleation step. For that, the “necking” stage, well established in Bridgman or Czochralski growth processes, has been successfully applied to the growth of 3C-SiC with the CF-PVT technique. This has allowed getting only one 3C-SiC crystal. The enlarged parts, after having passed the neck, are of high structural quality.