Growth of high-quality Ge epitaxial layers on Si(100)

A method of growing high-quality epitaxial Ge layers on a Si(100) substrate is reported. In this method, a 0.8 mum Si0.1Ge0.9 layer was first grown. Due to the large lattice mismatch between this layer and the Si substrate, many dislocations form near the interface and in the lower part of the Si0.1Ge0.9 layer. A 0.8 mum Si0.05Ge0.95 layer and a 1.0 mum top Ge layer were subsequently grown on the Si0.1Ge0.9 layer. The formed interfaces of Si0.05Ge0.95/Si0.1Ge0.9 and Ge/Si0.05Ge0.95 can bend and terminate the upward-propagated dislocations very effectively. The in situ annealing process was also performed for each individual layer. Experimental results show that the dislocation density in the top Ge layer can be greatly reduced, and the surface is very smooth, while the total thickness of the structure is only 2.6 mum.