2013 年 54 巻 10 号 p. 1905-1909
We have simulated the precipitation process in an amorphous Si/Ge multi-layer film, with and without Cu addition, by a molecular dynamics method. Four specimens were prepared for this study: Si/Ge layers, Si/(Ge + Cu) layers, (Si + Cu)/(Ge + Cu) layers and Si/Cu/Ge/Cu layers. After the multi-layered films became amorphous, we tracked the movement of individual atoms at 1000 K, the annealing temperature. When Cu was present in the Ge layer or both the Si and Ge layers, the precipitation of nano-clusters was less than that in Cu-free Si/Ge layers. We think that the Cu atoms block the precipitation and make the Si and Ge become more stable in the amorphous state. If Cu atoms are note present in a layer, however, like the Si layer in Si/(Ge + Cu) and Si/Cu/Ge/Cu specimens, the precipitation of nano-clusters in the Cu-free layer is enhanced. Therefore we conclude that precipitation of nano-clusters in Si/Ge layers can be controlled by how Cu atoms are added to the amorphous Si/Ge system, and that this will improve the thermoelectric performance.
