Thick 4H-SiC Epitaxial Growth and Defect Reduction for Very High Voltage Bipolar Devices

Abstract

The reduction of extended and point defects, including 8H in-grown stacking faults, basal plane dislocations (BPDs), and Z1/2 center, in 4H-SiC epitaxial layers was investigated. In the epitaxial growth process, a high density of 8H stacking faults was evaluated in the epilayer grown under a relatively high partial pressure of SiH4. By decreasing the SiH4 partial pressure or adding HCl to the conventional gas system (H2+SiH4+C3H8), the 8H stacking fault density was considerably reduced. By using 4° off-cut 4H-SiC substrates instead of an 8° off-cut one, an extremely low BPD density in the epilayer was achieved. No deep levels other than Z1/2 and EH6/7 centers were detected in the upper half of the bandgap for epilayers grown with the addition of HCl. The Z1/2 center concentration was reduced to <1 × 1012 cm−3 by tuning the growth parameters, and further reduced by the post-growth processes.

Time-resolved photoluminescence spectral analysis of phonon-assisted DAP and e-A recombination in N+B-dopedn-type 4H-SiC epilayers

“…Epilayers with thicknesses of 48-100 µm were grown on 4H-SiC (0 0 0 1) substrates with a 4° off-cut towards 11 20 by chemical vapor deposition, as specimens, using a vertical hot-wall reactor [14,15]. Nitrogen doping was performed by introducing N 2 gas.…”

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

“…Remarkable progress has been made in reducing defect density of SiC crystal wafers. However, the densities of TSD and TED are still on the order of 10 2 –10 3 and 10 3 –10 4 cm –2 , respectively. − …”

Characterization of V-Shaped Defects Formed during the 4H-SiC Solution Growth by Transmission Electron Microscopy and X-ray Topography Analysis

“…Meanwhile, several types of defects like carrot defects and comet defects formed during the chemical vapor deposition (CVD) growth of SiC have been reported. , It is well-known that defects in SiC have various deleterious effects on power device performances. − In order to realize the full potential of SiC power devices, the reduction of defects density becomes extremely crucial. Although many efforts have been done to decrease the density of defects, the dislocation density of thousands cm –2 still exists in SiC grown crystals by PVT and CVD growth. − …”