Capacitance transient study of the deep Fe acceptor in indium phosphide

We present a detailed study of the electrical properties of the deep Fe2+/3+ acceptor in InP by deep-level transient spectroscopy. The Fe acceptor transition has been observed in electron and hole emission in n- and p-type InP. A study of the electron emission signature reveals an electric-field enhancement of the emission rate, which is best explained by a polarization potential model. At 300 K electron and hole capture cross sections of 1.5×10^-17 and 4×10^-18cm² were determined, respectively, indicating the Fe acceptor being a recombination center. The capture cross sections were found to be temperature dependent in agreement with a multiphonon emission process with activation energies of 138±{}13 meV for electron and 161±{}15 meV for hole capture. Measurements of the Fe3+/2+ electron capture cross section at electric-field strengths above 4×10⁴V/cm reveal an approximately 70 times higher value of 1×10^-15cm² than without an electric field due to an electric-field-induced lowering of the capture barrier. This increase of the capture cross section is most likely due to a decreased capture barrier for electrons in the L valleys. Since the capture barrier is close to zero when an electric field is applied, the apparent activation energy of EC-0.62 eV, determined by deep-level transient spectroscopy from the carrier emission in an electric field, has not to be corrected by the zero-field capture barrier energy.