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 (SQ Ws) 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) im aging and photoluminescence spectroscopy techniques. Our results indicate a . significant improvement of the optical quality of the quaternary wells wi th increasing values of the cap layer thickness. Tensile and compressive st rained In1-xGaxAsyP1-y/InP SQWs grown with the same structure exhibited dif ferent relaxation processes, even when the strain magnitude was the same. P LM images of highly compressive quantum wells exhibited a large number of d ark Lines corresponding to misfit dislocations as a result of the partial r elaxation process in the well material. PLM images of similar tensile strai ned samples revealed only the presence of dark spots with no evidence of mi sfit dislocations.