Room-Temperature Ferromagnetism of Ga_1-xMn_xN Grown by Low-Pressure Metalorganic Chemical Vapour Deposition

Epitaxial films of Ga_1-xMn_xN have been grown on c-sapphire substrates by low-pressure metal-organic vapour phase epitaxy. The samples show ferromagnetic behaviour up to a temperature of T=380K with hysteresis curves showing a coercivity of 50--100Oe. No ferromagnetic second phases and no significant deterioration in crystal quality with the incorporation of Mn can be detected by high-resolution x-ray diffraction. The result of x-ray absorption near-edge structures indicates that Mn atoms substitute for Ga atoms. The Mn concentrations of the layers are determined to reach x=0.038 by proton-induced x-ray emission.