In this paper we develop a growth process for obtaining Bat and relaxed In0.2Ga0.8As layers on GaAs (0 0 1). The process designed is based on the results obtained by in situ and real time characterization of surface morphology and layer relaxation. In particular, our results show that for growth temperatures T-s less than or equal to 200 degreesC the relaxation of In0.2Ga0.8As layers is inhibited and the morphology does not evolve to a crosshatched pattern. After growth thermal treatments of these low-temperature (LT) In0.2Ga0.8As layers induce the development of a very faint (rms = 0.5 nm) crosshatched-like morphology. The relaxation process during the thermal annealing is strongly asymmetric and the layers present a high final strain state. By growing on top of the LT layer another In0.2Ga0.8As layer at higher temperature, relaxation is increased up to R approximate to 70% and becomes symmetric. Depending on the growth process of the top layers morphology evolution differs, resulting in better morphologies for top layers grow by atomic layer molecular beam epitaxy (ALMBE) at T-s = 400 degreesC. We have obtained 400 nm In0.2Ga0.8As layers with a final degree of relaxation R approximate to 70% and very flat surfaces (rms = 0.9 nm).