Model for ${\mathrm{Fe}}^{2+}$ intracenter-induced photoconductivity in InP: Fe

We have observed a broad, room-temperature photoconductivity band, with a peak at 0.44 eV, in Fe-doped InP. This band is attributed to an ${\mathrm{Fe}}^{2+}$ intracenter optical excitation, followed by a thermal excitation to the conduction band. We derive a photoconductivity expression which takes into account optical and thermal transitions between impurity ground and excited states, within the band gap, and the conduction band. The parameters yielded by the model include a thermal excitation prefactor of 1×${10}^{11}$ ${\sec }^{-1\mathrm{}}$, an electron capture cross section of 1×${10}^{-15\mathrm{}}$ ${\mathrm{cm}}^2$, a spontaneous recombination coefficient of 1×${10}^6$ ${\sec }^{-1\mathrm{}}$, and an Fe concentration of 2×${10}^{16}$ ${\mathrm{cm}}^{-3\mathrm{}}$. The experimental temperature dependence of the photoconductivity is in the right direction, but is smaller than predicted by the model.