Raman scattering study of the clustering phenomena in InGaAsP grown by LPE on (100) and (111) GaAs

In order to investigate the short range ordering, the asymmetric broadening of the Raman spectra of InGaAsP grown on GaAs substrate has been studied with the spatial correlation model. The broadening phenomena was found to be enhanced in the region of immiscibility, in agreement with the photoluminescence observation. But, in Raman measurements, the clustering effect has been found to occur even out of the miscibility gap. The effect is more enhanced in samples grown on (100) substrate than in samples grown on (111)A substrate. This shows that the stabilization of the growth due to the strain has also had a role to restrict the formation of the clustering in the growth process.