Effects of implantation dose on the inhomogeneous broadening of zero phonon lines in LiF

Abstract

The inhomogeneous broadening and line shape of the F 4 (1) zero phonon line in LiF at 2.366 eV, measured at 4 K, has been used to probe the environment of these defects and the presence of internal strain as a function of implantation dose. Measurements on LiF implanted with 1 MeV protons at room temperature show substantial broadening of the zero phonon line. Studies of low and high dose γ-irradiated samples are used for comparison purposes. The observed broadening in the proton implanted specimens shows irregularities which is compared with the growth and collapse of colour centre concentrations previously reported in the literature. The results suggest two regimes: a low dose region where broadening results from point defects and small point defect aggregates and a high dose region where extended defects are, to a significant extent, responsible. Line shape analysis is consistent with these conclusions.