An investigation was made of InGaAs layers with InGaAs graded layers on GaAs . layers that had been grown on Si substrates using metal-organic vapour phase epitaxy. Cross-sectional transmission electron microscopy revealed that dislocations propagating from the GaAs layer were bent in the graded layer, thereby reducing the density of threading dislocations in the InGaAs layer. Thermal cyclic annealing was performed for GaAs layers. The threading dislocation density in the InGaAs layer decreased with decreasing threading dislocation density in the GaAs layer. The combination of an InGaAs graded layer with thermal cyclic annealing of the GaAs layer was effective for reducing the threading dislocation density of the InGaAs cap layer. The respective threading dislocation densities of In0.095Ga0.905As and In0.22Ga0.78As layers with InGaAs graded layers were 1.3 x 106 and 4.4 x 106/cm2 when thermal cyclic annealing was performed four times at 850C for GaAs layers.

Threading Dislocations in InGaAs Cap Layers with InGaAs Graded Layers Grown on Si Substrates. Y.Takano, K.Kobayashi, T.Uranishi, S.Fuke: Japanese Journal of Applied Physics, 2010, 49[10], 105502