Robert Tyler Leonard

Direct Determination of Burgers Vectors of Threading Mixed Dislocations in 4H-SiC Grown by PVT Method

In addition to pure threading screw dislocations (TSDs), the presence of threading mixed dislocations (TMDs) (with a component) has been reported both in 4H-SiC axial slices (wafers cut parallel to the growth axis) and in commercial offcut wafers (cut almost perpendicular to the growth axis). In this paper, we first demonstrate a method to quickly distinguish TMDs from TSDs in axial slices via synchrotron white-beam x-ray topography. Since such axial slices are usually not available for commercial purposes, a systematic method is then developed and demonstrated here to unambiguously determine the Burgers vectors of TMDs in 4H-SiC commercial offcut wafers. In this second study, both synchrotron monochromatic-beam x-ray topography and ray-tracing simulation are used. The x-ray topographs were recorded using grazing-incidence geometry. The principle of this method is that the contrast of dislocations on different reflections varies with the relative orientation of Burgers vectors with respect to the diffraction vectors. Measurements confirm that, in a commercial offcut wafer, the majority of the threading dislocations with screw component are mixed-type dislocations.

Growth and Characterization of Semiconductor Silicon Carbide for Electronic and Optoelectronic Applications: An Industrial Perspective

Publisher Summary During the past decade, silicon carbide (SiC) semiconductor device technology for electronic and optoelectronic applications has made tremendous progress resulting primarily from the commercial availability of SiC substrates of ever increasing diameter and quality. Throughout the technical evolution of semiconductor SiC, the fabrication of SiC crystals exhibiting the desired electrical and crystalline properties has played a central role in the realization of the full potential of this important semiconductor material. The aim of this chapter is to discuss, from an industrial viewpoint, the current state of SiC crystal growth technology and to present empirical results that reflect the recent advances in SiC crystal growth. Recent progress in the development of the physical vapor transport (PVT) technique for SiC bulk growth has led to substrate diameters up to 100-mm, residual impurities in the lO15 cm-3 range, thermal conductivity approaching 5.0 W/cmK in bulk crystals, transparent 6H and 4H-SiC at crystal diameters up to 75-mm, and micropipe densities as low as 0.9 cm-2 over a 50-mm diameter 4H-SiC wafer. These advances help to position SiC for an exciting future and provide a sound foundation for the realization of the full potential of SiC for high power density electronic devices, optoelectronic devices of high brightness, and SiC materials applications requiring low optical absorption.