Determination of the correlation between the crystal field axis system and the crystallographic axes in chromium‐doped β‐Ga₂O₃ by EPR

Abstract

The correct relationship is found between the crystal field axes and crystallographic axes in P-Ga,O, b y application of a simplified orientation method. A computer program is set up, which is able to calculate and to plot the angular variation of the resonance field strengths and of the energy levels involved in EPR. In this way, the strange angular dependence of the E P R lines can be explained and the correctness of the stated correlation between the two axis systems can be verified. From the measured resonance fields a set of spin Hamiltonian parameters is calculated.Durch Anwendung einer vereinfachten Orientierungsmethode gelingt es, die wahre Beziehung zwischen Kristallfeldachsen und kristallogrnphischen Achsen in P-Ga,O, herauszufinden. Es wird ein Computer-Programm geschrieben, das in der Lage ist, die Winkelabhlngigkeiten von Resonanzfeldstarken und ESR-Energieniveaus zu berechnen und graphisch darzustellen. Auf diese Weise kann die ungewohnliche Winkelabhlngigkeit der ESR-Linien erklart und die Richtigkeit der gefundenen Beziehung zwischen den beiden Achsensystemen nachgewiesen werden. Aus den gemessenen Resonanzfeldstarken wird ein Gatz von Spin-Hamilton-Parametern berechnet.

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

“…The errors in Table I arise from the slight sample misalignment, and not from the large linewidth. 20 The solid lines in Figs. The monoclinic term confirms that the local site symmetry of Cr 3ϩ in the ␤-Ga 2 O 3 crystal is monoclinic, rather than orthorhombic.…”

“…A total number of 316 resonance line positions due to the fine structure of Cr 3ϩ in ␤-Ga 2 O 3 recorded in the three crystallographic planes was used for fitting the SH parameters. 20 For orthorhombic symmetry, the principal axes of the g and D tensors should coincide and the resonance fields should all be symmetric about the extrema in the three principal crystallographic planes; this, however, was not the case. In our room temperature experiments, the signs of the ZFS parameters were not determined.…”

“…The angle of rotation around the y axis required to reduce the monoclinic parameter B 2 1 to zero is ␣ϭ20.3°. 20 The parameters were calculated in the three principal axes which are not clearly mentioned. 35 Gunsser and Rohwer obtained g XX ϭ1.976Ϯ0.004, g Y Y ϭ1.9787Ϯ0.0007, g ZZ ϭ1.9797Ϯ0.0006, ͉D͉ϭ4680Ϯ5, and ͉E͉ϭ2054Ϯ2 for Cr 3ϩ in an orthorhombic SH.…”

“…19 Doped impurities that give rise to microscopic structural change affect the optical properties of the crystal, depending on site location and local symmetry of the impurities. 20. Electron paramagnetic resonance ͑EPR͒ is a sensitive and powerful technique for investigating site location and the local site symmetry of impurities in the host material.…”

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

“…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.…”