The effects of strain and In content on dislocation reduction was studied by introducing an InGaAs strained layer into a GaAs layer on a Si substrate. The two effects were separated by using the strain energy that accumulates in the InGaAs layer, since the strain in an InGaAs layer varies with In content. The results show that the variation in dislocation density depends on the strain and not on the In content. A strain energy of 250 dyn/cm was sufficient for effectively reducing dislocations in both the InGaAs layer and in the GaAs overlayer. However, when the strain energy was over 500 dyn/cm, the number of dislocations increased when an InGaAs layer was introduced. ©1995 American Institute of Physics.