Correlation of the structural and ferromagnetic properties of Ga1-xMnxN grown by metalorganic chemical vapor deposition

Metalorganic chemical vapor deposition (MOCVD) has been used to grow high-quality epitaxial films of Ga1-xMnxN of varying thickness and manganese doping levels. No macroscopic second phases were observed via high resolution X-ray diffraction. Atomic force microscopy revealed MOCVD-like step flow growth patterns with a mean surface roughness as low as 3.78 (A) over circle in lightly doped samples, and matched that of the underlying GaN template layers. No change in the growth mechanism and morphology with Mn incorporation is observed. A uniform Mn concentration in the epitaxial layers is confirmed by secondary ion mass spectrometry. SQUID measurements showed an apparent RT ferromagnetic hysteresis with saturation magnetizations as high as 2.4 mu(B)/Mn at x = 0.008, which decreases with increasing Mn incorporation or reduced structural quality. Co-doping with either Si or Mg during the resulting growth process resulted in a large decrease in the saturation magnetization values. Competition for incorporation between Mn and Mg during the MOCVD growth process is observed. (c) 2005 Elsevier B.V. All rights reserved.