SIMS Analysis of Fe Impurity Concentration in a PVT-Grown 4H-SiC Bulk Crystal and Source Powders

Abstract

Iron (Fe) impurity concentrations in a SiC bulk crystal and source powders used for the bulk crystal growth are analyzed by means of secondary ion mass spectrometry and the validity of the obtained data are discussed. The secondary ion signal of56Fe is found to be affected significantly by the mass interference of28Si2, and therefore measurements of54Fe instead of56Fe offer a better detection limit for the analysis. A high concentration of Fe is found at proximity of the SiC bulk crystal surface. Possible sources of the Fe contamination are discussed based on the depth profile data of Fe in both the bulk crystal and the source powders.