Electron paramagnetic resonance of thermal donors in germanium

At least two new electron-paramagnetic-resonance (EPR) spectra were observed in oxygendoped germanium. One of them, which is ascribed to thermal donors, reveals C₂ᵥ symmetry in agreement with similar centers in silicon. The results are explained in terms of defects compressing the neighboring lattice along a [110] direction. Another spectrum exhibits probably C₃ᵥ symmetry, but its correspondence with thermal donors remains speculative. The EPR results also show that the effective spin of these centers should be larger than {}.