Elastic stress relaxation in GaInAsP quantum wires on InP

High resolution x-ray diffractometry and photoluminescence measurements (PL ) have been used to compare the effects of elastic stress relaxation of fre e standing and overgrown Ga0.22In0.78As0.80P0.20 quantum wire structures on InP. The elastic relaxation occurs near the free surface of the sidewalls resulting only in a minor shift of the PL line. The overgrowth of the struc tures with a Ga0.22In0.78As0.16P0.84 layer, which has a residual tensile st rain of more than 1% compared with the InP substrate, leads to a strong inc rease of the PL line shift. At the same time, a shift of the x-ray diffract ion pattern from the small angle side of the InP peak to the large angle si de is observed. In addition, the diffuse scattering increases. The strain f ields in the wire structures are calculated, and the diffraction patterns a re determined from the strain maps in the kinematical approximation.