Abstract
Unintentionally doped n-type β-Ga2O3 becomes highly resistive after annealing at high temperatures in oxygen ambient. The annealing process also induces an electron paramagnetic resonance (EPR) center, labeled IR1, with an electron spin of S = 1/2 and principal g-values of gxx = 2.0160, gyy = 2.0386, and gzz = 2.0029 with the principal axis of gzz being 60° from the [001]* direction and gyy along the b-axis. A hyperfine (hf) structure due to the hf interaction between the electron spin and nuclear spins of two equivalent Ga atoms with a hf splitting of ∼29 G (for 69Ga) has been observed. The center can also be created by electron irradiation. Comparing the Ga hf constants determined by EPR with corresponding values calculated for different Ga vacancy-related defects, the IR1 defect is assigned to the double negative charge state of either the isolated Ga vacancy at the tetrahedral site (V2−Ga(I)) or the VGa(I)–Gaib–VGa(I) complex.
Highlights
) structure due to the interaction between the electron spin and the nuclear spins of two equivalent Ga atoms
Comparing the Ga hf constants determined by electron paramagnetic resonance (EPR) with corresponding values calculated for different Ga vacancy-related defects, the IR1 defect is assigned to the double negative charge state of either the isolated Ga vacancy at the tetrahedral site (VG2Àa(I)) or the VGa(I)–Gaib–VGa(I) complex
In a later EPR study of n-type and Fe-doped semi-insulating b-Ga2O3 irradiated with protons, Bardeleben and co-workers8 observed two EPR centers (EPR1 and EPR2) having an electron spin of S 1⁄4 1/2 and a hf structure from a hf interaction with two equivalent Ga atoms
Summary
Comparing the Ga hf constants determined by EPR with corresponding values calculated for different Ga vacancy-related defects, the IR1 defect is assigned to the double negative charge state of either the isolated Ga vacancy at the tetrahedral site (VG2Àa(I)) or the VGa(I)–Gaib–VGa(I) complex. In neutron-irradiated b-Ga2O3, Kananen et al.7 observed an EPR spectrum with S 1⁄4 1/2, showing a hyperfine (hf) structure due to the interaction between the electron spin and the nuclear spins of two equivalent Ga atoms.
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