InN films were grown by N2 plasma-assisted molecular beam epitaxy (MBE) on Al2O3 substrates. The films were characterized by reflection high-energy electron diffraction, atomic force microscope, x-ray diffraction methods and Raman spectrum, indicating high crystalline quality of the films. The optical absorption and photoluminescence measurement show the band-gap energy of InN films was located about 1.0-1.1 eV.
InN-based diluted magnetic semiconductor (DMS) In1-xMnxN and In1-xCrxN films were prepared by N2 plasma-assisted MBE at low temperature. Microstructure characterization indicates Mn was homogeneously incorporated into InN up to 4% and 10% respectively at 300°C and 200°C, while Cr was incorporated up to 4% at 300°C. A paramagnetic to spin-glass transition was observed at 3 K in In0.9Mn0.1N films grown at 200°C. Room temperature ferromagnetism was observed for the homogeneous In0.98Cr0.02N films.
Transition metal doped III-V nitrides including Mn- or Cr-doped GaN and InN are grown by molecular beam epitaxy (MBE). Structural, electronic and magnetic properties have been investigated. Cr-doped GaN shows room temperature ferromagnetism. Bulk sensitive high-energy x-ray photoemission spectroscopy is performed at SPring-8 to elucidate electronic structure of Cr-doped GaN. It is found that the doped Cr contributes to form gap states, which pin the Fermi level. The gap state is attributed to Ga 4s originated state caused by strong hybridization between Cr 3d and band electrons of host GaN. InN-based system were grown by low temperature MBE. Highly Mn-doped InN shows spin-glass states. Anti-ferromagnetic interaction between Mn ions in InN was suggested. Contrary to the Mn-doped InN, Cr-doped InN shows ferromagnetic property at room temperature.
Pr1-xSrxMnO3 (100) thin films were prepared on NdGaO3 (100) substrate by RF-plasma-assisted molecular beam epitaxy method. The films were characterized by reflection high-energy electron diffraction, atomic force microscope and x-ray diffraction methods, indicating perfect surface smoothness and high crystalline quality. Large low field magnetoresistance effects with strong anisotropic properties of the non-stoichiometric (Pr1-xSrx)yMnO3 films have been observed. These results may be connected with the large A-site deficient in the films.