In situ optical monitoring of metalorganic vapor phase epitaxy growth of C-doped GaAs

Metalorganic vapor phase epitaxy (MOVPE) growth of heavily carbon doped GaA s on undoped GaAs substrates has been studied by reflectometry with a 632.8 -nm laser beam. Small changes in the refractive index due to high carbon do ping densities (10(20) cm(-3) and above) induce oscillations in the reflect ed intensity. The evolution of the layers morphology is shown to depend on two effects: (i) the locally high surface concentration of carbon which blocks locally t he growth and hence induces holes at the surface, (ii) the occurrence of dislocations at thicknesses larger than the critical thickness which are revealed chlorides produced by the decomposition of CC l4 (the carbon precursor) and form deep etch pits.