Long tail Zn diffusion in InGaAsP and InGaAlAs quaternary alloys

We investigated the Zn diffusion characteristics in InGaAsP and InGaAlAs quaternary alloys, which are commonly used as the active layers of long wavelength optical communication devices. The measured Zn diffusion profiles of InGaAsP and InGaAlAs alloys had long tails while those of InP and InAlAs alloys were quite abrupt, indicating a clearly observable difference between quaternary alloys and others. Since these tails could be well fitted by using the group-V vacancy related defect model, its mechanism seems to be closely related with group-V atomic bonds. We also found that the group-V vacancies related to Ga atoms, particularly for those originating from GaP bond, had a significant influence on this type of Zn diffusion.