The unintentional redistribution of Zn during the annealing (650 to 724C) of heterostructures, of InGaAsP on Zn-doped InP, was investigated. A sudden increase in the hole concentration was observed in the quaternary alloy while, in the vicinity of the hetero-interface, the adjacent InP layer exhibited hole concentrations which were up to an order of magnitude lower than those in the bulk. Numerical simulations which took account of Zn diffusion via mono-vacancy and di-vacancy complexes, in addition to the usual substitutional-interstitial mechanism, indicated that a considerable number of immobile mono-vacancy complexes were incorporated into the InP during epitaxial growth. The mobile di-vacancy complex, which was in equilibrium with the mono-vacancy complex, penetrated the quaternary layer; where it was incorporated as an electrically active impurity.

E.Peiner, K.Hansen, M.Lübbe, A.Schlachetzki: Japanese Journal of Applied Physics, 1996, 35[1-2A], 557-63