Photoionization cross section of InP:Fe

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Abstract
The spectral dependence of the photoionization cross section of Fe doped in InP is determined by photocapacitance spectroscopy. The optical process of the carrier emission from the deep acceptor level of Fe is discussed from the results. For the crystal-field-split level of Fe2+:5E, the photoionization cross sections for the fundamental transitions of 5E→Γ1 and Γ15→5E are adequately described by the Lucovsky model. Those optical thresholds are 0.63 and 0.78 eV, respectively, at 77 K. In comparison with the deep-level transient spectroscopy measurements, the following conclusions are obtained. The energy separation between the Fe acceptor level and the conduction-band edge is constant, but that between the Fe level and the valence-band edge varies correspondingly to the temperature variation of the InP band-gap energy. The fact that there is no difference between the optical and thermal activation energies for the 5E→Γ1 transition indicates that the Fe acceptor level is not perturbed by the InP lattice vibration.