In-plane strain and strain relaxation in laterally patterned periodic arrays of Si/SiGe quantum wires and dot arrays

The depth dependent strain relaxation in photolithographically defined and reactive ion etched Si/SiGe quantum wire and dot arrays is determined by high resolution grazing incidence x-ray diffraction. The laterally periodic structures were aligned along two orthogonal [110] and [1̄10] directions on the (001) surface. By recording reciprocal space maps around the (220) and (2̄20) reciprocal lattice points, the shape and in-plane strain could be determined independently of each other. Using triple axis diffractometry and changing the effective penetration depth of the x-ray radiation between 5 and 300 nm the strain relaxation in the wires and dots could be determined depth resolved.