Electron Paramagnetic Resonance of Iron in Gallium Arsenide

Abstract

The electron paramagnetic resonance spectrum of iron in GaAs has been studied at 9 Gc/sec. The spectrum corresponds to a spin $\frac{5}{2}$ in a cubic environment and can be described by the two parameters in the spin Hamiltonian $g=2.0462\mathrm{}\pm 0.0006$ and $a=(+339.7\mathrm{}\pm 0.3)\times {10}^{-4\mathrm{}}$ ${\mathrm{cm}}^{-1\mathrm{}}$ at 1.3°K and $g=2.0453\mathrm{}\pm 0.0008$ and $a=(+342.2\mathrm{}\pm 0.5)\times {10}^{-4\mathrm{}}$ ${\mathrm{cm}}^{-1\mathrm{}}$ at 77°K. The iron apparently substitutes for the Ga and is observed when the defect is neutral. The temperature-independent linewidth of 54 G is attributed to hyperfine interaction with neighboring nuclei. If the interaction is assumed to be appreciably only with nearest neighbors, then the hyperfine constant is about 10 G. In addition to the allowed transitions, nine of the ten possible "quasiforbidden" transitions between states for which the strong-magnetic-field quantum number differs by more than one unit have been identified. The angular dependence of the spectrum has been studied with the magnetic field in the ($1\overline{1}0$) plane. The positions and intensities of the transitions are found to agree in detail with those calculated from the spin Hamiltonian, except that the over-all intensity of the "quasiforbidden" transitions is some 5 to 10 times too weak. The spin Hamiltonian with the Zeeman energy diagonal is given in its complete form for the magnetic field in the ($1\overline{1}0$) plane, from which a number of the qualitative features of the intensities of the "quasiforbidden" transitions are readily obtained.