Real-time optical monitoring of semiconductor epitaxial growth

We report on time-resolved Reflectance Anisotropy Spectroscopy (RAS) measurements carried out during the molecular beam epitaxial growth of GaAs (001). Growth started on a c(4x4) reconstructed surface which changed to (2x4) and then to (4x) as growth progressed. We found that reflectance anisotropy spectra comprise three components, each one with a specific physical origin and determine their time evolution as a function of epitaxil film thickness. We conclude that RAS is a powerful probe for the monitoring and potentially for the control of epitaxial growth.