The interdiffusion of superlattice structures, during annealing at temperatures of between 700 and 850C, was studied by means of Raman spectroscopy. The peak intensities and peak energies of InAs-, GaAs-, and InP-like longitudinal optical phonon modes varied as a function of annealing temperature and time. The depth profiles of group-III and group-V atoms were estimated quantitatively by monitoring variations in the peak energies of the longitudinal optical phonon modes, and in the ratios of the mode intensities. This revealed that the interdiffused superlattice consisted of InGaAsP of uniform composition, and InP barrier layers with sharp interfaces. It was found that the resultant InGaAsP well was roughly lattice-matched to InP (to within 0.5%). The diffusion coefficient in the well region was larger than that in the barrier region, and the interdiffusion could be described by:

D(cm2/s) = 8.56 x 1010 exp[-5.82(eV)/kT]

Interdiffusion in this superlattice was governed by diffusion in the InP region.'

S.J.Yu, H.Asashi, S.Emura, S.Gonda, K.Nakashima: Journal of Applied Physics, 1991, 70[1], 204-8