High Fe2+/3+ trap concentration in heavily compensated implanted InP

Abstract.

High Fe concentrations (up to 2×10¹⁹ cm^-3) have been implanted in n-doped InP to compensate the substrate donors. The resulting semi-insulating layers have been investigated by current–voltage (I-V) measurements and photo-induced current transient spectroscopy (PICTS) analyses to characterise the Fe activation process and to study the Fe related deep levels. The activation of the Fe^2+/3+ trap has been assessed by the identification of the deep level located at E_C-0.64 eV. The outcomes of the PICTS measurements have been correlated with the electrically active Fe concentration calculated from a numerical simulation of the I-V characteristics. We observe an increasing linear relation between the electrically active Fe concentration and the substrate doping density, with a maximum active Fe concentration as high as 2×10¹⁸ cm^-3, i.e. more than an order of magnitude above the equilibrium Fe solid solubility. These data are presented and their implications discussed.