Strain and relaxation processes in In1-xGaxAsyP1-y/InP single quantum wells grown by LP-MOVPE

Strained and partially relaxed In1-xGaxAsyP1-y/lnP single quantum wells (SQWs) with different cap layer thicknesses and biaxial strain values grown by low-pressure metalorganic vapor phase epitaxy (LP-MOVPE) were investigated by double crystal X-ray diffraction, photoluminescence microscopy (PLM) imaging and photoluminescence spectroscopy techniques. Our results indicate a. significant improvement of the optical quality of the quaternary wells with increasing values of the cap layer thickness. Tensile and compressive strained In1-xGaxAsyP1-y/InP SQWs grown with the same structure exhibited different relaxation processes, even when the strain magnitude was the same. PLM images of highly compressive quantum wells exhibited a large number of dark Lines corresponding to misfit dislocations as a result of the partial relaxation process in the well material. PLM images of similar tensile strained samples revealed only the presence of dark spots with no evidence of misfit dislocations.