To prevent components associated to dislocations in the measured

To prevent components associated to dislocations in the measured RD spectra, a 0.3μm thick GaAs buffer layer was grown prior to carrying out the experiments. Further, to avoid electro-optical contributions that may hinder the analysis of the RD line shapes, we did not intentionally dope the GaAs films.
In Fig. 1 we show time-resolved RD spectra of GaAs homoepitaxy for (a) PAs=6×10−7Torr and (b) PAs=5×10−6Torr. Lowermost spectra in both cases correspond to GaAs surfaces under As flux, just before starting growth. For PAs=6×10−7PAs=6×10−7 the LY2584702 of the RD spectrum is rather involved. This is in correspondence with the evolution of the GaAs surface reconstruction which changes from c(4×4)c(4×4) before starting growth, to (2×4)(2×4) after the deposition of about 0.5 ML GaAs, and to a Ga-rich (4×2)(4×2) phase after steady state growth is reached. In comparison, the RD spectrum evolution for PAs=5×10−6Torr is simpler according to the less varied surface reconstruction changes. We note, nevertheless, that irrespective of PAs values, there is a change in RD spectrum line shape as growth progresses.