Molecular beam epitaxy of strained Si1−xGex layers on patterned substrates

Epitaxial Si_1-xGe_x layers have been grown on patterned Si(001) substrates. Mesa-like structures of 1.4 μm height on the surface limited by inclined {111} planes were used. Structure dimensions between 10 and 0.2 μm were chosen to allow the mesas to relieve elastically under the strained layer. The film growth, the crystallographic perfection and the relaxation of strained Si_1-xGe_x layers were investigated by transmission electron microscopy (TEM) including in situ annealing. The relaxation mechanism and the control of dislocation generation on top of the mesas are discussed.