Growth and characterization of low-temperature grown GaN with high Fe doping

We succeeded in growing highly Fe-doped GaN films by solid-source molecular beam epitaxy using an electron-cyclotron-resonance microwave nitrogen plasma. The substrate temperature was in the range of 380–520 °C. The samples were analyzed by x-ray diffraction and transmission electron microscopy, and showed hexagonal (wurtzite) or cubic (zincblende) structure or a mixture of both phases. The Fe concentration was on the order of ${10}^{19} {\mathrm{cm}}^{\text{−3}}$ and extended x-ray absorption fine structure data show that the Fe is substituting the Ga in GaN. The magnetization measurements as a function of temperature reveal ferromagnetic properties below 100 K for the sample grown at the lowest temperature.