Residual strain and threading dislocation density in InGaAs layers grown on Si substrates by metalorganic vapor-phase epitaxy

Abstract

InGaAs layers with In contents between 0.007 and 0.055 have been grown on GaAs epilayers on Si substrates by low-pressure metalorganic vapor-phase epitaxy. The threading dislocation density of the order of 105 cm−2 in the InGaAs layer was achieved by insertion of an InGaAs strained layer combined with thermal cycle annealing. Photoluminescence measurement for layers confirmed that the residual strain was lower in InxGa1−xAs layers with x⩾0.038 than that in GaAs. It is suggested that the tensile strain due to the difference in the thermal expansion coefficient between InGaAs and Si materials was compensated by the compressive strain partly due to the slow strain relaxation by work hardening in InGaAs layers grown on GaAs layers or due to the incomplete strain relaxation in InGaAs layers at the small thickness of 1 μm.