Activation of Fe doping and electrical compensation in semi-insulating InP

The impurity distribution, doping activation mechanism, and interaction between Fe atoms and point defects in Fe-doped and annealed undoped semi-insulating (SI) InP materials are compared. The substitution and activation of Fe occur mostly via an interstitial hopping mechanism in as-grown Fe-doped SI InP. However, Fe atoms aggregate around dislocations and form complex defects with vacancies. The concentration of Fe atoms at interstitial positions is very high, resulting in a low activation efficiency. The activation mechanism of Fe is a kick-out substitution process in SI material obtained by annealing undoped InP in an iron phosphide ambient. Fe atoms nearly completely occupy the indium lattice sites due to the indium vacancy in the material before annealing. The formation of deep level defects is suppressed in the annealing process. This results in high Fe activation efficiency and good electrical properties of the SI-InP material.