Colloidal Silicon-Germanium Nanorod Heterostructures

Colloidal nanorods with axial Si and Ge heterojunction segments were produced by solution-liquid-solid (SLS) growth using Sn as a seed metal and trisilane and diphenylgermane as Si and Ge reactants. The low solubility of Si and Ge in Sn helps to generate abrupt Si-Ge heterojunction interfaces. To control the composition of the nanorods, it was also necessary to limit an undesired side reaction between the Ge reaction byproduct tetraphenylgermane and trisilane. High-resolution transmission electron microscopy reveals that the Si-Ge interfaces are epitaxial, which gives rise to a significant amount of bond strain resulting in interfacial misfit dislocations that nucleate stacking faults in the nanorods.