Electrical and optical properties of defects in silicon introduced by high-temperature electron irradiation

2-MeV electron irradiation of Si at elevated temperature creates a dominant deep level at the energy $E_c$-0.36 eV in addition to the oxygen vacancies. This level, which is less significant in room-temperature-irradiated Si, is found to be an efficient recombination center in the present situation. The optical cross section of this level measured by deep-level optical spectroscopy reveals a fine structure superimposed on the main transition. This fine structure is considered to be related to a new resonant phonon mode coupled with the above defect. The isochronal annealing behavior shows that this defect might be a kind of vacancy-oxygen complex. With the assumption of a $V_2$-${\mathrm{O}}_2$ complex structure, a calculation based on the Green’s-function method of lattice dynamics indicates the existence of a defect-induced resonant phonon mode with energy of 10 meV, which is in good agreement with the experimental observation.