Polycrystalline silicon germanium thin films prepared by aluminum‐induced crystallization

Abstract

AbstractThe aluminum‐induced crystallization (AIC) of amorphous silicon germanium (a‐SiGe) was investigated in bilayer structure of aluminum (Al) and a‐SiGe at the eutectic temperature of Al–Ge system (420 °C) or higher temperature. Due to energy dispersive X‐ray spectroscopy (EDX) measurements after the AIC at 420 °C, crystallized SiGe alloys are formed with island structures and Al locates between the islands. The layer‐exchange is confirmed in the island regions. In the AIC at 450 °C, similar island structures are observed but the Ge is sometimes found with Al probably due to the eutectic. The layer‐exchange of SiGe seems incomplete. On the other hand, Si and Ge are separately localized in the AIC at 500 °C, which is observed by the EDX images and also suggested by the Raman and X‐ray diffraction (XRD) measurements. Probably, the eutectic helps to segregate Ge from SiGe alloys. We confirm that thermal annealing above the eutectic temperature of Al and Ge is not suitable for the AIC of a‐SiGe and the segregation of Si and Ge prevents the complete layer exchange.