The Nucleation and Propagation of Threading Dislocations with C-Component of Burgers Vector in PVT-Grown 4H-SiC

Abstract

Studies of threading dislocations with Burgers vector of c+a have been carried out using synchrotron white beam X-ray topography. The nucleation and propagation of pairs of opposite sign threading c+a dislocations is observed. Overgrowth of inclusions by growth steps leads to lattice closure failure and the stresses associated with this can be relaxed by the nucleation of opposite sign pairs of dislocations with Burgers vector c+a. Once these dislocations are nucleated they propagate along the c-axis growth direction, or can be deflected onto the basal plane by overgrowth of macrosteps. For the c+a dislocations, partial deflection can occasionally occur, e.g. the a-component deflects onto basal plane while the c-component continuously propagates along the growth direction. One factor controlling the details of these deflection processes is suggested to be related to the ratio between the height of the overgrowing macrostep and that of the surface spiral hillock associated with the threading growth dislocations with c-component of Burgers vector.

Analysis of reaction between c+a and -c+a dislocations in GaN layer grown on 4-inch Si(111) substrate with AlGaN/AlN strained layer superlattice by transmission electron microscopy

“…While the mutual interaction of threading c+a and -c+a dislocations during cooling also forms 2a dislocation, this phenomenon was observed in bulk 4H-SiC by cross-sectional X-ray topography. 30,31 In this case, 2a dislocations are limited to the segment where the c+a and -c+a dislocations interact and both sides of the 2a dislocation are constructed from c+a and -c+a dislocations. Recently, we found that a complex dislocation both sides of an a 1 dislocation segment consist of a 2 and a 3 dislocations (a 1 =a 2 +a 3 ).…”

Material science and device physics in SiC technology for high-voltage power devices

“…101) Recent studies using synchrotron X-ray topography revealed that the majority of TSDs possess a Burgers vector of 1c + a. 102,103) This means that these TSDs are not pure screw dislocations, but mixed dislocations.…”

Bulk and epitaxial growth of silicon carbide

“…TSDs usually propagate almost along the <0001> direction. Recent studies using synchrotron x-ray topography revealed that many of TSDs possess a Burgers vector of c + a [55,56], which means that a significant portion of TSDs is not of pure screw type but mixed dislocations. TSDs are basically replicated from a seed crystal.…”