Electron paramagnetic resonance spectroscopy of lithium donors in monoisotopic silicon

摘要

Electron paramagnetic resonance (X-band EPR) spectra are reported for lithium-related donors in monoisotopic silicon. High resolution EPR spectra of lithium donor centers in monoisotopic silicon, enriched by ~(28)Si isotope (99.99%) with very narrow individual lines are observed. In monoisotopic silicon sample (~(28)Si enriched floating zone silicon with low concentration of lithium ～10~(16)cm~(-3)), the trigonal EPR spectrum, with well resolved ~7Li hyperfine structure is recorded in the temperature range 3.5-20 K. This spectrum was attributed to LiO complex. At high concentration of lithium (about 10~(18) cm~(-3)) in monoisotopic silicon two types of spectra are observed. The trigonal one has the same feature as for low concentration of lithium with g-values: g_‖ = 1.9974 and g_⊥ = 1.9989. Another spectrum consists of two lines and has tetragonal symmetry with g,, = 1.9992 and g±_⊥= 1.9983. This spectrum is more intensive than the trigonal one and has no resolved hyperfine structure probably due to time averaging of the hyperfine interaction caused by hopping motion of electrons.