STRAIN RECOVERY IN PARTIALLY RELAXED IN0.2GA0.8AS GAAS SINGLE QUANTUM-WELLS WITH INCREASING GAAS CAP LAYER THICKNESS/

The effect of cap layer thickness on residual strain in partially rela xed, 250 A thick In0.2Ga0.8As/GaAs single quantum well structures was examined by photoluminescence, transmission electron microscopy and hi gh-resolution x-ray diffraction. When the cap layer thickness increase d from 50 to 5000 angstrom, the residual strain increased from 0.88% t o the misfit value of 1.4%. As a consequence the cap layer thickness s hould be taken as a parameter, along with misfit and growth temperatur e, to determine critical layer thickness in lattice-mismatched single quantum well structures.