Electrically detected magnetic resonance of phosphorous due to spin dependent recombination with triplet centers in γ-irradiated silicon

Electrically detected magnetic resonance (EDMR) of phosphorus in silicon was detected in weak magnetic fields at low resonance frequencies of 200-400 MHz before and after irradiation of samples by γ-rays. EDMR spectra were detected by measuring dc-photoconductivity of samples under band-gap illumination. Phosphorus (P0) EDMR lines are accompanied always with the single line (S-line) with g-factor ∼2.01 originated most likely from the surface recombination centers. Strong, about 10 times, increase of the P0 and S signals was found in the same samples after irradiation with the doses of (3-6)x1015 γ/cm-2. For these doses of irradiation we were also able to see the ESR transition between entangled states of phosphorous formed at low magnetic field. This shows the higher efficiency of spin dependent recombination (SDR) process in irradiated samples. In addition, several new EDMR lines emerged after irradiation. Some of them arose from the spin dependent recombination through the photoexcited triplet states of A-centers (oxygen+vacancy complex).