Molecular Beam Epitaxy of Wurtzite GaN-Based Magnetic Alloy Semiconductors

The preparation of hexagonal GaN:Mn and GaN:Fe epilayers has been studied by RF-plasma-assisted molecular beam epitaxy. GaN:Fe epilayers exhibit superparamagnetic behavior, presumably due to ferromagnetic inclusions. GaN:Mn epilayers can be expressed in the form of Ga 1- x Mn x N with x up to 0.02, indicating the successful preparation of the GaN-based magnetic alloy semiconductor for the first time. The epilayers are primarily paramagnetic and highly resistive. For epilayers with very high Mn concentration (∼ 10 21 cm -3 ), analysis of the paramagnetic component has revealed the effective spin number S ≈2.5 together with the positive paramagnetic Curie temperature. This suggests the presence of ferromagnetic spin exchange between Mn ions.