Surface Morphology Transformation Under High-Temperature Annealing of Ge Layers Deposited on Si(100)

We study the surface morphology and chemical composition of SiGe layers after their formation under high-temperature annealing at 800-1100 degrees C of 30-150 nm Ge layers deposited on Si(100) at 400-500 degrees C. It is found that the annealing leads to the appearance of the SiGe layers of two types, i.e., porous and continuous. The continuous layers have a smoothened surface morphology and a high concentration of threading dislocations. The porous and continuous layers can coexist. Their formation conditions and the ratio between their areas on the surface depend on the thickness of deposited Ge layers, as well as on the temperature and the annealing time. The data obtained suggest that the porous SiGe layers are formed due to melting of the strained Ge layers and their solidification in the conditions of SiGe dewetting on Si. The porous and dislocation-rich SiGe layers may have properties interesting for applications.