Electron spin resonance of platinum pair complex in silicon

We investigated a Pt-Pt pair in Si by electron spin resonance (ESR) measurement. Two kinds of ESR spectra from Pt-Pt pairs which had been already reported were not detected. However, we observed other ESR spectrum of Pt-Pt pair. The ESR spectrum showed the hyperfine structure corresponding to two equivalent Pt atoms. The anisotropic g-tensor obtained by analyzing the angular dependence of the ESR signals indicated the orthorhombic (C2v) symmetry with the g-values of gx=2.11, gy=2.31, gz=2.09. The gz axis was along [0 0 1] direction. The gy and gz axes were along [1 1 0] and [1¯10] directions, respectively. The ESR spectrum of Pt-Pt pair was observed in the sample only under illumination. This suggests that a change in the charge state of Pt-Pt pair is caused by carrier excitation.