Real-time reflectance-difference spectroscopy during the epitaxial growth of InAs/GaAs/(001)

Highlights: • Real-time reflectance-difference spectroscopy of InAs quantum dots growth. • Measurements carried out at a rate of 10 spectra per second. • In situ, real-time monitoring and study of the kinetics of InAs quantum dot formation. • Demonstration of the existence of a precursor stage for the growth of quantum dots. - Abstract: We report on real-time Reflectance-difference spectroscopy measurements carried out during the growth of InGaAs quantum dots (QD́s) on GaAs (001) substrates. Measurements were performed with a recently developed rapid RD spectrometer, at a rate of 10 spectra per second. Our results demonstrate the potential for RD spectroscopy as an optical probe for the real-time monitoring of the epitaxial growth of InAs/GaAs QD́s. We show that RD provides information on the kinetics of formation of QD́s, including the rate of InAs coverage of the GaAs substrate and the rate of growth of InGaAs QD́s. Results further suggest that the formation of QD́s is mediated by the formation of InAs-rich islands that eventually disappear as QD́s mature.