A detailed study of the electrical properties of the deep Fe2+/3+ acceptor was performed using deep-level transient spectroscopy, since an Fe acceptor transition had been observed during electron and hole emission in n-type and p-type InP. A study of the electron emission signature revealed an electric-field enhancement, of the emission rate, which was best explained in terms of a polarization potential model. At 300K, electron and hole-capture cross-sections of 1.5 x 10-17 and 4 x 10-18cm2, respectively, were determined. This indicated that the Fe acceptor was a recombination center. The capture cross-sections were found to be temperature dependent, in agreement with a multi-phonon emission process with activation energies of 0.138eV for electron capture and 0.161eV for hole capture. Measurements of the Fe2+/3+ electron-capture cross-section, at electric-field strengths above 4 x 104V/cm, revealed an approximately 70 times higher value (10-15cm2) than that in the absence of an electric field. This was due to an electric field-induced lowering of the capture barrier. This increase in the capture cross-section was attributed to a decreased capture barrier for electrons in the L valleys. Since the capture barrier was close to zero when an electric field was applied, an apparent activation energy of Ec - 0.62eV, determined via deep-level transient spectroscopy of carrier emission in an electric field, did not have to be corrected by the zero-field capture barrier energy.

A.Dadgar, R.Engelhardt, M.Kuttler, D.Bimberg: Physical Review B, 1997, 56[16], 10241-8