Deflection of Threading Dislocations with Burgers Vector c/c+a Observed in 4H-SiC PVT–Grown Substrates with Associated Stacking Faults

Abstract

A review is presented of Synchrotron White Beam X-ray Topography (SWBXT) studies of stacking faults observed in PVT-Grown 4H-SiC crystals. A detailed analysis of various interesting phenomena were performed and one such observation is the deflection of threading dislocations with Burgers vector c/c+a onto the basal plane and associated stacking faults. Based on the model involving macrostep overgrowth of surface outcrops of threading dislocations, SWBXT image contrast studies of these stacking faults on different reflections and comparison with calculated phase shits for postulated fault vectors, has revealed faults to be of basically four types: (a) Frank faults; (b) Shockley faults; (c) Combined Shockley + Frank faults with fault vector s+c/2; (d) Combined Shockley + Frank faults with fault vector s+c/4.

Effects of defects in a 4H-SiC material on the breakdown behavior of a Schottky barrier diode

“…The reduction of extended defects in the epilayer is a key issue in the field of high quality device fabrication. Epitaxial defects such as pits, 28 carrots, 9,31,32 and stacking faults 16,33 are caused by TSDs in the substrate. In most cases, substrate TSDs are either inherited from the seed crystal, or formed during growth.…”

“…A 6 inches n-type 4H-SiC substrate with an off-cut angle of 4°f rom [0001] toward the [11][12][13][14][15][16][17][18][19][20] direction was prepared, and labeled as Substrate-A. A SiC epitaxial layer with a thickness of 10 μm on Substrate-A was grown, noted as Epitaxy-B.…”

“…10,12,13 By current understanding, TEDs were considered as benign defects, as the least harmful defect to devices. In contrast, studies show that TSDs lead to a high reverse-current leakage and a lower reverse breakdown voltage, 15 and overgrown screw dislocations can cause Frank and Shockley stacking faults, 16 which deteriorate the performance of SiC devices. With more studies on the failure principle of SiC devices, several reports have proposed that emission microscopy could be used to confirm the leakage current in epilayers.…”

Analysis of Dislocation Contrast in Synchrotron Grazing-incidence X-ray Topographs and Ray-tracing Simulation in Off-axis 4H-SiC Crystals

“…Extensive studies on these various dislocations have been reported by many research groups. Dudley et al reported on the deflection of TSDs/TMDs by the overgrowth of macro-steps to form stacking faults [4][5][6]. Inter-conversion between BPDs and TEDs has also been reported by Wang et al due to the step interaction on the growth interface which results in hopping Frank-Read Sources in 4H-SiC [8].…”

Conversion Behavior of Threading Screw Dislocations on C Face with Different Surface Morphology During 4H-SiC Solution Growth

“…As a consequence, ultra-high-quality SiC grown crystals can be obtained. Dudley et al pointed out that the interaction of macrostep and threading dislocation was responsible for the conversion of threading dislocation during PVT growth. − Yamamoto et al reported that the conversion phenomenon depended on the polarity of the growth surface, Si face and C face. On the Si face, TSD conversion frequently occurred, but no TSD conversion was observed on C face solution growth due to the absence of macrosteps .…”