Bulk Growth and Characterization of SiC Single Crystal

Abstract

Sublimation method was used to grow bulk SiC by J.A. Lely for the first time in 1955 (Lely, 1955). It was improved then by Tairov and Tsvetkov and became the most mature method for bulk SiC growth. In this chapter, we will introduce the growth of hexagonal SiC. Although the bulk growth method is well known and used widely, there are still plenty of details which are different and unique for different groups. The growth of 4H-SiC is not as stable as that of 6H-SiC. That is to say the growth of 4H-SiC needs a harsh growth conditions. In order to grow high quality 4H polytype, the polytype transition of 4H-SiC single crystals had been studied. Although single crystals of SiC are commercially available, owing to the specific structures of SiC, there are still some structural defects, such as micropipes, mis-orientations, dislocations, stacking faults, basal plane dislocations, particle inclusions, precipitates and so on, which hinder its applications. So in this chapter we also introduce the recent progress in research of structural defects in 6H-SiC single crystals. Three kinds of typical structural defects in 6H-SiC single crystals were investigated. First, we describe the strain field of a micropipe by the theory of screw dislocation. Stress birefringence images from micropipes with different Burgers vectors have been simulated. The results are compared with polarized optical microscopic observations. Second, elementary screw dislocations were observed by back-reflection synchrotron radiation topography (BRSRT). Based on the reflection geometry, the image of an elementary screw dislocation was simulated. Elementary screw dislocation is a pure screw dislocation with Burger vector lc. Finally, Basal plane bending was detected by high resolution X-ray diffractometry (HRXRD) and transmission synchrotron white-beam x-ray topography (SWBXT). The observation and investigation of the structural defects helped us to understand their formation mechanisms. This makes it possible for us to further decrease or eventually eliminate them.