No abstract

No abstract

We present a study of the influence of gallium vacancy (V Ga) point defects on the ferromagnetic properties of GaN:Mn and GaN:Mn,O micro-and nanostructures. Results demonstrate that the generation of these point defects enhances the ferromagnetic signal of GaN:Mn microstructures, while incorporation of oxygen as an impurity inhibits this property. XPS measurements revealed that Mn impurities in ferromagnetic GaN:Mn samples mainly exhibit a valence state of 2þ. Cathodoluminescence (CL) spectra from Mn-doped GaN samples displayed emissions centered at about 1.97 eV, attributed to transitions between the 4 T 1-6A 1 states of the Mn 2þ d orbitals, and emissions centered at 2.45 and 2.9 eV, associated with the presence of V Ga. CL measurements also revealed a blue shift of the GaN band-edge emission generated by the expansion of the wurtzite lattice due to Mn incorporation, which was confirmed by XRD measurements. These latter measurements also revealed an amorphization of GaN:Mn due to the incorporation of oxygen as impurities. The GaN:Mn samples were synthesized by thermal evaporation of GaN and MnCO 3 powders onto Ni 0.8 Cr 0.2 /Si(100) in a horizontal furnace operated at low vacuum. The residual air inside the system was used as a source of oxygen during the synthesis of Mn and O co-doped GaN nanostructures. Mn and O impurities were incorporated into the nanostructures at different concentrations by varying the growth temperature. Energy Dispersive Spectroscopy, XRD, and XPS measurements confirmed that the obtained samples predominantly consisted of GaN.

No abstract

No abstract