Investigations of 3C-SiC inclusions in 4H-SiC epilayers on 4H-SiC single crystal substrates

Abstract

Synchrotron white beam x-ray topography (SWBXT) and Nomarski optical microscopy (NOM) have been used to characterize 4H-SiC epilayers and to study the character of triangular inclusions therein. 4H-SiC substrates misoriented by a range of angles from (0001), as well as (1 100) and (112 0) oriented substrates were used. For epilayers grown on substrates misoriented by 3.5 ~ from (0001) toward <1120>, the triangular inclusions were identified as consisting of two 3C-SiC structural configurations which are related to each other by a 180 ~ rotation about the [111] axis. The epitaxial relationships between the 3C inclusions and the 4H-SiC epilayers (or substrates) were also determined. No evidence was found for the nucleation of 3C-SiC inclusions at superscrew dislocations (along the [0001] axis) in the 4H-SiC substrates. Increasing the offaxis angle of the substrates from 3.5 to 6.5 ~ was found to greatly suppress the formation of the triangular inclusions. In the case of substrates misoriented by 8.0 ~ from (0001) toward <1120>, the triangular inclusions were virtually eliminated. The crystalline quality of 4H-SiC epilayers grown on the substrates misoriented by 8.0 ~ from (0001) was very good. For the (1100) and (1120) samples, there is no indication of 3C-SiC inclusions in the epilayers. Possible formation mechanisms and the morphology of 3C-SiC inclusions are discussed.

Formation of extended defects in 4H‐SiC epitaxial growth and development of a fast growth technique

“…The most common polytype inclusions in 4H-SiC epilayers are 3C inclusions. Various types of defects with a cubic stacking sequence, which are named triangular defects or 3C platelets and comet defects, have been reported [7][8][9][10]28]. The triangular defects were reported to degrade the reverse blocking performance of 4H-SiC pn diodes by Kimoto et al [25].…”

“…Defect densities in typical off-angled 4H-SiC epilayers can be 10 2 -10 4 cm -2 for threading screw dislocations (TSDs) with Burgers vector of 1c[0001], 10 3 -10 5 cm -2 for threading edge dislocations (TEDs) with Burgers vector of 1/3〈1120〉 type and 10 0 -10 3 cm -2 for basal plane dislocations (BPDs) with Burgers vector of 1/3〈1120〉 type [2,3]. Other types of extended defects, such as carrot defects [4,5], basal plane Frank-type defects [6], 3C inclusions [7][8][9][10] and 8H stacking faults [11,12], may also be present in 4H-SiC epilayers. The impact of extended defects on the electrical characteristics of devices may vary depending on the defect structure.…”

Structure and Morphology of Inclusions in 4° Offcut 4H-SiC Epitaxial Layers

“…Polytype inclusions have been reported to form in 8°offcut SiC epilayers, and they also have shown poor surface morphology. [13][14][15][16][17][18] These previous reports discuss inclusions containing 3C-SiC regions such as the arrow defect, which has a large 3C particulate and an arrow-shaped surface feature in the step-flow growth direction. Another inclusion is the comet defect, which shows a small 3C-SiC region and a tail-like region showing surface morphology.…”

Dislocation nucleation in 4H silicon carbide epitaxy

“…en et al [5] reported that low angle grain boundaries composed of threading edge dislocations reduce the minority carrier lifetime. These dislocations were shown to be due to pre-existing dislocations in the substrates which propagated into the epilayers during the homoepitaxy [6,7]. In addition, degradation of SiC p-i-n diodes has recently attracted much attention [8].…”