High-resolution photoinduced transient spectroscopy as a new tool for quality assessment of semi-insulating InP

High-resolution photoinduced transient spectroscopy has been applied to study grown-in defect centres in semi-insulating InP:Fe. The defect structure of crystals characterized by various values of Hall mobility has been compared. A number of defect centres with activation energies ranging from 10 to 640 meV were detected. They include shallow donor and acceptor impurities, native defects, shallow impurity-native defect complexes and iron-related defects. It was found that the Hall mobility is mainly affected by the shallow donor concentration which determines the ratio [Fe2+]/[Fe3+]. The electron lifetime is determined either by the iron concentration or the concentration of shallow impurities.