On the electrical activity of Fe in LEC indium phosphide

A model for the incorporation of electrically active Fe in LEC InP is prese nted. The concentration of Fe-active in a given cross section of the ingot is expressed as a function of the corresponding grown fraction and the peri od of time between the solidification of that particular cross section and the end of the pulling. Implicitly, this means that the Fe activity depends on the thermal history and the concentration of In vacancies of that cross section. The final relationship accounts well for experimental results suc h as (i) an Fe activation higher in the crystal top with respect to the cry stal tail and (ii) an Fe activation slightly higher in crystals pulled at l ower speed.