Synchrotron White Beam X-Ray Topography and High Resolution X-RayDiffraction Studies of Defects in SiC Substrates, Epilayers and Device Structures

Abstract

A general review will be presented of recent Synchrotron White Beam X-ray Topography (SWBXT) studies of defects in SiC single crystals and epitaxial layers carried out at Stony Brook and at the Stony Brook Synchrotron Topography Station at the National Synchrotron Light Source, Brookhaven National Laboratory. Results will be presented from studies of (a) 4H and 6H-SiC substrates growth by Physical Vapor Transport, (b) homoepitaxial layers grown on such substrates, (c) hetereoepitaxial layers grown on 4H substrates, and (d) SiC device structures. SWBXT results will be correlated with those from AFM, Nomarski Optical Microscopy, High Resolution X-ray Diffraction (HRXRD), SEM and TEM studies carried out on the same crystals. From (a), substrate defects observed include closed-core and hollow-core screw dislocations (micropipes) in 6H and 4H, deformation-induced basal plane dislocations in 6H and 4H; and small angle boundaries in 4H. The close correlation between simulated and observed back-reflection, grazing-incidence reflection and transmission SWBXT images of screw dislocation will be discussed. From (b) results from studies of the correlation between substrate and epilayer defects in 6H/6H homoepitaxial layers will be presented. From (c) polytype mapping in 3C/4H-SiC heterostructures will be described. The relationship between substrate and epilayer defects will again be explored as will the lattice mismatch between epilayer and substrate as indicated by a combination of SWBXT and HRXRD.