Ge fraction dependence of Al-induced crystallization of SiGe at low temperatures

Al-induced crystallization of Si_1-xGe_x films (x=0-0.5) has been investigated by using amorphous SiGe (a-SiGe)/Al structures to realize polycrystalline SiGe (poly-Si) layers on in-sulating films at low temperatures. For the Si sample, poly-Si oriented to the (111) direction was formed after annealing (450 °C, 20 h) and inversion of Si/Al layers occurred completely. For Si_1-xGe_x samples (x > 0), the layer exchange occurred in partial areas and poly-SiGe with the (111) orientation was grown only in the exchanged areas. The Ge fractions of the crystallized SiGe were almost the same as those of the initial a-SiGe layers. The diameters of the crystallized areas decreased from ∼100 (x = 0) to ∼30 μm (x = 0.5) with increasing Ge fraction. This technique can be utilized for the formation of high-quality poly-SiGe at low temperatures.