Correlation of the structural and ferromagnetic properties of Ga 1−xMn xN grown by metalorganic chemical vapor deposition

Abstract

Metalorganic chemical vapor deposition (MOCVD) has been used to grow high-quality epitaxial films of Ga 1− x Mn x N 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 Å 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 μ 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.