In situ observation of ellipsometry monolayer oscillations of metalorganicvapor-phase epitaxy-grown III-V compound materials

Oscillations of the ellipsometry signal were clearly seen during metalorgan ic vapor-phase epitaxy (MOVPE) of III-V materials under high sample rotatio n at 1400 rpm. The ellipsometric signal oscillated at a period correspondin g to 1 monolayer of MOVPE growth. Agreement was excellent between growth ra te data from the oscillation period and that from thickness measurements af ter growth(deviation: < 1%). Oscillations correlated with the formation of islands due to nucleation on terraces during the growth of 1 monolayer. The effective medium dielectric response of smooth and rough surfaces appears responsible for different ellipsometry signals. Layer thickness and the InG aAs composition were precisely determined in situ. Critical layer thickness and In composition for InGaAs quantum dot formation were also evaluated di rectly from in situ ellipsometry data. (C) 2000 Elsevier Science B.V. All r ights reserved.