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

Abstract

The structure of inclusions and their influence on surface morphology, local strain, and basal plane dislocations were investigated in silicon carbide (SiC) epitaxial layers grown on 4°offcut substrates. On high-resolution x-ray topography images, strain fields were observed surrounding the inclusions. Ultraviolet photoluminescence images revealed the presence of strain-induced dislocations around the inclusions. Micro-Raman and microphotoluminescence spectroscopy showed that the inclusions exhibited a complex structure that consisted of 3C polytype regions and misoriented 4H polytype regions. The resulting lattice deformation typically propagates in the step-flow growth direction and causes distorted surface morphology.

Silicon Carbide Epitaxy

“…The defect is bound by two basal plane partial dislocations producing two etch pits at the corners of the fault intersecting the surface. The 3C inclusions can have a morphology quite similar to the faults shown in Figure 28.16 [95][96][97]. The TEM cross-section identified the defect as the single unit cell of the 8H polytype of SiC.…”

Characterization of 4H- and 6H-Like Stacking Faults in Cross Section of 3C-SiC Epitaxial Layer by Room-Temperature μ-Photoluminescence and μ-Raman Analysis

“…SFs are wrong sequences of the double layers and they can be seen as inclusions of a few layers of an SiC polytype in the perfect layer stacking of another polytype [15]. It is known that the TO mode for 4H-SiC lattice is located at 778 cm −1 [16]. Thus, we think that the area of the µ-Raman map (reported in Figure 4b) characterized by the presence of the peak at 778.3 cm −1 is an area with a high density of defects.…”

Bulk and epitaxial growth of silicon carbide

“…It has been reported that both in-grown stacking fault and triangular 3C inclusion densities increase with increase of the growth rate [161], decrease of the offangle [162,163], and decrease of the growth temperature. A majority of these SFs are caused by slips in basal planes (Shockley type), but Frank type SFs are also observed [164].…”