The effect of barrier strain in +1.65%-strained In0.77Ga0.23As/InGaAs multiple quantum wells was investigated by means of double-crystal X-ray diffraction, transmission electron microscopy and room-temperature photoluminescence techniques. The optimum condition of the barrier layer, as deduced from X-ray and photoluminescence measurements, was near to lattice-matching. That is, a strain of between -0.40 and +0.20% was required for sharp X-ray diffraction satellite peaks, and between -0.17 and +0.14% for a high photoluminescence intensity. Misfit dislocations were introduced into the multiple quantum well structures under compressive strain in the barrier layer. In the case of tensile strains, threading dislocations originated from thickness undulations in the wells, and barriers were observed. Transmission electron microscopy revealed that the thickness undulations were caused by compositional modulations. The undulation and modulation were increased by increasing the tensile strain in the barrier layers.

Effect of Strain in the Barrier Layer on Structural and Optical Properties of Highly Strained InGaAs/InGaAs Multiple Quantum Wells M.Mitsuhara, M.Ogasawara, H.Sugiura: Journal of Crystal Growth, 2000, 210[4], 463-70