Strain relaxation studied by photoluminescence and by double crystal X-ray diffraction measurements in strained InGaAs

Photoluminescence (PL) and double crystal X-ray diffraction (DCXD) experiments have been carried out on strained View the MathML sourceAs grown on InP substrate by molecular beam epitaxy with different epilayer thicknesses, in order to study lattice relaxation. Samples with tensile strain (View the MathML source) and compressive strain (View the MathML source) have been investigated. Strain was measured by DCXD in conjunction with detailed rocking curve analysis within a dynamical framework. From PL results, we have evaluated the strain values in two different ways. First, we used the PL transition shift induced by strain and second, from PL temperature dependence we measured the heavy-hole-light-hole splitting, which is a direct measurement of strain. Our results have shown good agreement between PL and DCXD measurements and also the existence of residual strain even in samples with a thickness considerably greater than the critical layer thickness.