UNINTENTIONAL REDISTRIBUTION OF ZN IN INGAASP INP HETEROSTRUCTURES/

The unintentional redistribution of Zn during annealing of InGaAsP/InP :Zn heterostructures at 650 to 724 degrees C was investigated. An abru pt increase of the hole concentration p was observed in the quaternary alloy while in the vicinity of the heterointerface the adjacent InP l ayer exhibited values of p which are by up to an order of magnitude lo wer than in the bulk. Both effects adversely affect the performance of double-heterostructure laser diodes. Numerical simulations taking Zn diffusion via monovacancy and divacancy complexes in addition to the c ommon substitutional-interstitial mechanism into account indicate that a considerable number of immobile monovacancy complexes are incorpora ted into the InP during epitaxy. The mobile divacancy complex, which i s in equilibrium with the monovacancy complex, penetrates the quaterna ry layer where it is incorporated as an electrically active impurity.