A study of iron incorporation in LEG-grown indium phosphide

We have studied iron segregation in Czochralski-grown InP as a function of the pulling and cooling rates, We observed that the Fe-active/Fe-total ratio can be modified by varying these growth parameters. The activation ratio, which is normally between 0.60 and 0.70 for pulling rates of 8-10 mm/h, is found to be slightly higher corresponding to low pulling rates (2-3 mm/h) and considerably lower for pulling rates > 14 mm/h. Furthermore, we observed that the electrical properties and wafer uniformity are improved in crystals pulled at the lowest rates. The experimental results are discussed considering that low pulling and cooling rates correspond to an in situ annealing of the InP crystal. The principal aim of this work is that of increasing the fraction of electrically active Fe atoms in InP crystals grown by the liquid encapsulation Czochralski method.