A study was made of intrinsic and impurity-related defects in SiC epilayers grown via fast epitaxy, using chemical vapor deposition in a vertical hot-wall reactor. Using capacitance transient techniques, low concentrations of electron traps (denoted by Z1/2, EH6/7 and Ti) and hole traps (denoted by HS1 and shallow B) were detected in the n-type 4H–SiC epilayers. The concentrations of intrinsic defects (Z1/2, EH6/7, and HS1 centers) increased with increasing growth temperature. The incorporation of shallow B decreased at higher growth temperatures, whereas the Ti concentration was not sensitive to the growth temperature. The concentrations of shallow B and Ti increased with increasing C/Si ratio. However, the concentrations of the EH6/7 and the HS1 centers decreased with increasing C/Si ratio. Graphite susceptors with a TaC or SiC coating were also tested, and it was observed that the purity of the susceptor material played a critical role in reducing the background impurity incorporation. A correlation with the carrier lifetimes of these epilayers indicated that the EH6/7 and Z1/2 centers might be the lifetime-limiting defects in the investigated epilayers.

Electrically Active Defects in n-Type 4H–Silicon Carbide Grown in a Vertical Hot-Wall Reactor. J.Zhang, L.Storasta, J.P.Bergman, N.T.Son, E.Janzén: Journal of Applied Physics, 2003, 93[8], 4708-14