On the electrical activity of Fe in LEC indium phosphide

Abstract

A model for the incorporation of electrically active Fe in LEC InP is presented. 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 period 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 such as (i) an Fe activation higher in the crystal top with respect to the crystal tail and (ii) an Fe activation slightly higher in crystals pulled at lower speed.

Uniformity of semi-insulating InP wafers obtained by Fe diffusion

“…It is also important to note that the great majority of the diffused Fe atoms seems to be electrically active, in contrast to the case of as-grown LEC InP where the fraction of active Fe is about 0.3-0.7 of the total, depending on growth conditions and axial position of the wafer. 12 An example of a resistivity map is shown in Fig. 1.…”