IN-SITU OBSERVATION OF DIFFUSION AND SEGREGATION OF Fe ATOMS IN Si CRYSTALS AT HIGH TEMPERATURE BY MOESSBAUER SPECTROSCOPY

摘要

We perform "high-temperature" Moessbauer experiments on silicon wafers with 30 at. ppm ~(57)Fe in the temperature range from 20°Cto 1100°C using an UHV-furnace. Different phases of Fe-silicides such as ξ_β and ξ_α-FeSi_2 are identified in the spectra at elevating experimental temperatures. At 1100°C, the precipitates of ξ_α-FeSi_2 dissolve completely, leading to an "Fe solid solution" in Si matrix. This component is tentatively assigned to "substitutional Fe", which performs atomic jumps with the jump frequency of 10~7 s~(-1) at 1000°C, although the concentration of 30 at.ppm Fe is far above the reported solubility.