EPR study of hydrogen-related radiation-induced shallow donors in silicon

An electron paramagnetic resonance (EPR) study of hydrogen-related radiatio n-induced shallow donors in silicon has been performed. Three species of th is donor family (D1-D3) were observed earlier by means of infrared absorpti on measurements in hydrogenated Czochralski-grown Si (Cz-Si) crystals after irradiation with fast electrons and subsequent annealing in the temperatur e range of 300 to 550 degrees C. An EPR signal with isotropic g-factor of 1 .9987, labeled TU1, has been found in hydrogenated Ct-Si crystals which wer e irradiated and annealed at 300 to 350 degrees C. It was shown that the TU 1 signal is related to the shallow donor state of the D1 center. Annealing at temperatures higher than 350 degrees C resulted in transformation of the D1 to the D2 centers. This led to the transformation of the TU1 spectrum t o another one with S = 1/2 and anisotropic g-tensor, the principal values o f which were found to be very close to those for the Si-NL10 EPR spectra in silicon. The observed EPR spectra are compared with the Si-NL10 ones and p ossible atomic structures, and formation mechanisms of the defects which gi ve rise to these spectra are discussed.