Electron paramagnetic resonance characterization of Cr3+ impurities in a β-Ga2O3 single crystal

Abstract

␤-Ga 2 O 3 single crystals doped with the Cr 3ϩ ion were grown in an O 2 atmosphere using the floating zone method. Electron paramagnetic resonance ͑EPR͒ spectra of the Cr 3ϩ ion were recorded with an X band EPR spectrometer at 20°C. The rotation patterns of Cr 3ϩ spectra in the crystallographic planes together with spin-Hamiltonian parameters showed unequivocally that the actual local site symmetry of the Cr 3ϩ ion in ␤-Ga 2 O 3 is not orthorhombic, as previously reported, but monoclinic. The spectroscopic splitting tensor g and the zero-field splitting parameters B k q s were determined with an effective spin Hamiltonian. The Cr 3ϩ ions replace Ga 3ϩ ions in oxygen octahedra rather than in oxygen tetrahedra. The energy levels of the ground state of a Cr 3ϩ ion embedded in the ␤-Ga 2 O 3 crystal were calculated.

Antiferromagnetic superexchange interaction between Fe3+ ions in Fe3+ doped wide-gap oxide of β-Ga2−Fe O3 (x=0.1, 0.2, 0.3, 0.4)

“…The properties of β-Ga 2 O 3 , such as transportation [4][5][6][7][8][9], magnetism [10][11][12][13][14], and photoluminescence [15][16][17][18], can be greatly affected by the substitution of Ga 3 þ ions with the doped impurities. The previous investigations on the doping of β-Ga 2 O 3 indicate that compared with the Ga 3 þ ion ( $ 0.62 Å), the doped ion with a larger radius, such as Ti 4 þ [6], Cr 2 þ [19,20], Mn 2 þ [21,22], Fe 3 þ [23,24], In 3 þ [25,26], Er 3 þ [27], and Eu 3 þ [28], tends to occupy the B sites, while the doped ion with a smaller radius prefers to sit at the A site, such as Be 2 þ [26], and Si 4 þ [14].…”

Dopant activation in Sn-doped Ga2O3 investigated by X-ray absorption spectroscopy

“…29,30 For the ALD and PLD amorphous thin-films, the average coordination number to O atoms in such phenomenon has been observed in crystalline ZnO:Ga. 31 Lastly, post-annealing has been performed in this work in an attempt to activate the dopants in ALD Ga2O3:Sn thin-films (1 hour in N2 atmosphere at 1000ºC). However, both the film resistivity and crystalline order did not exhibit any detectable change and the authors are of the opinion that it might be necessary to anneal the films beyond 1000ºC to achieve crystalline Ga2O3 for dopant activation.…”

“…shown that transition metals like In, 28 Cr, 29 and Mn 30 have a preference for the octahedral site and can be explained by steric reasons. 29,30 For the ALD and PLD amorphous thin-films, the average coordination number to O atoms in such phenomenon has been observed in crystalline ZnO:Ga. 31 Lastly, post-annealing has been performed in this work in an attempt to activate the dopants in ALD Ga2O3:Sn thin-films (1 hour in N2 atmosphere at 1000ºC).…”

Study of nuclear quadrupole interactions and quadrupole Raman processes of 69Ga and 71Ga in a β-Ga2O3:Cr3+ single crystal

“…Single crystals of b-Ga 2 O 3 doped with Cr 3+ (0.05 mol%) were grown using a floating zone method [14]. Crystallographic axes were determined by the X-ray Laue approach.…”

“…These studies, which disclosed all 69 Ga and 71 Ga resonances, yielded eight sets of NMR parameters; these eight sets of resonance lines originated from a twin structure. Also, electron paramagnetic resonance (EPR) studies of Cr 3+ [13,14] in b-Ga 2 O 3 single crystals have been reported.…”