Influence of Ga vacancies, Mn and O impurities on the ferromagnetic properties of GaN micro- and nanostructures

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.

Cu(i) substituted wurtzite ZnO: a novel room temperature lead free ferroelectric and high-κ giant dielectric

“…Fig. 4 shows a typical magnetization vs. magnetic eld (M-H) curve obtained from a Zn 0.95 Cu 0.05 O 1Àd sample at 300 K, revealing a clear diamagnetic behavior under applied magnetic elds up to AE5 T. 30,31 Beside that, at magnetic intensities lower than AE0.2 T, the material exhibited a residual ferromagnetic signal, evident aer a subtraction of the diamagnetic signal as shown in the inset of Fig. 4.…”

“…4. 30,31 The diamagnetic behavior of Zn 0.95 Cu 0.05 O 1Àd is largely due to presence of fully lled d orbital of Zn 2+ and Cu + having electronic conguration 3d 10 4s 0 4p 0 . The weak ferromagnetism in Zn 0.95 Cu 0.05 O 1Àd can be originated due to the polarization of unpaired 2p electrons of O with the empty 4p orbital of Zn and Cu around oxygen vacancies in wurtzite lattice.…”

Carbon and Manganese in Semi-Insulating Bulk GaN Crystals

“…According to Reshchikov et al [ 40 , 43 ] and Xu et al [ 44 ], emission close to 2.4 eV and 2.9 eV can be associated with the presence of isolated gallium vacancies ( ) or their complexes. The generation of in the GaN:Mn samples can be correlated to an excessive distortion of the GaN lattice due to the high Mn incorporation [ 45 ]. Additionally, found DAP peaks may be caused by transitions of electrons from donors (in the case of HVPE-GaN crystals: Si Ga or O N , which are shallow donors) to shallow acceptors [ 44 , 46 ].…”

Mixed N,O‐donor Directed Blue Emissive Nano‐dispersed Mesoporous Mn(II)‐MOF: Dual Sensing Probe for Recyclable and Ultrasensitive ppb‐Level Recognition of TNP and Cr(VI)‐Oxoanions

“…[60] Furthermore, analysis of the deconvoluted spectra (Figure 3h) of Mn2p showed three peaks at 640.93 eV (2p 3/2 ), 645.22 eV (2p 3/2 , MnÀ O bonds) and 652.84 eV (2p 1/2 ). [62,[64][65][66] The functional groups as well as MnÀ O, MnÀ N binding present in the MOF-scaffold was identified by FT-IR spectroscopy (vide Figure S13, SI). First, the spectrum of phen can be divided into two frequency regions, 700-900 cm À 1 and 1400-1650 cm À 1 ; wherein sharp bands at ~735 cm À 1 and 854 cm À 1 may be attributed to the out of plane CÀ H deformation (ν 11 mode of pyridines in phen) and Hs attached with the central ring, respectively.…”