In Situ Spectral Reflectance Investigation of InAs/GaAs Heterostructures Grown by MOVPE

Metalorganic vapor-phase epitaxy of InAs/GaAs heterostructures was monitored in situ by spectral reflectance in the wavelength range from 600 nm to 1000 nm. Three-dimensional (3D) plots of reflectivity as a function of time and wavelength were used to determine the growth rate evolution. Theoretical simulation of reflectivity signals was carried out by combining a transfer matrix method and a multi-sublayer model. In spite of fixed growth parameters, there was temporal variation of the growth rate. By adjusting simulated reflectivity curves, optical constants of the InAs layer at 450°C were determined. The E1 critical point energy was also found experimentally at this temperature. Good agreement with calculated values is obtained.