Accurate flux estimation during molecular beam epitaxy growth of vertical-cavity surface-emitting lasers

We report an in-situ method for accurate flux monitoring in gas-source molecular-beam epitaxy (GSMBE) growth of vertical-cavity surface-emitting lasers (VCSELs). The method uses a single reflectivity spectrum measurement on the incomplete structure to estimate the values of the effusion cell fluxes (and therefore the thickness and the composition of the different layers) used for the growth of the first part of the device. The flux values are extracted using a simulated annealing algorithm. Before completing the structure, corrections are made in order to centre the cavity resonance of the final device at the desired wavelength.