Study of the relaxation process during InGaAs/GaAs (001) growth from in situ real-time stress measurements

Strain evolution during In0.2Ga0.8As/GaAs (001) growth by molecular beam epitaxy has been monitored in real time. We have detected that three main relaxation stages, related to different mechanisms, take place during growth, and we have obtained the thickness range where those mechanisms are active. The in situ measured relaxation behavior in the plastic stages has been described by means of a simple equilibrium model that takes into account dislocations generation and interaction between them. The excellent agreement between the experimental data and the model allows us to determine the value of the formation energy per unit length of a misfit dislocation and the extent of the interaction between dislocations in this material system.The authors would like to acknowledge F. Briones, J. P. Silveira, and J. M. García for their help with the experimental setup for the in situ measurements and valuable discussions. This work was supported by Spanish ‘‘CICYT’’ under Project No. MAT2000-1625. One of the authors (M.U.G.) thanks the Consejería de Educación y Cultura de la Comunidad de Madrid for funding.Peer reviewe