Uniaxial stress measurements on the 1039.8 meV zero-phonon line in irradiated silicon.

Abstract

A vibronic band in Si with its zero-phonon line at 1039.8 meV is a product of neutron irradiation and annealing at 500 to 800 K. We show that uniaxial stresses perturb the zero-phonon line as expected for a tetragonal centre. Since the TA(X) phonons are particularly important in forming the phonon sideband, we suggest that the tetragonal symmetry is a result of a naturally axial centre, and is not a Jahn-Teller distortion of a T d centre. No stress-induced reorientation of the centre occurs at small stress perturbations, but when the zero-phonon line splitting is comparable with the TA(X) energies the high energy stress-split component decreases rapidly in intensity. The zero-phonon line is negligibly affected by magnetic fields of up to 5 Tesla.