Linewidths of the electronic excitation spectra of donors in silicon

The excitation spectra of phosphorus, arsenic, isolated interstitial lithium, and lithium oxygen donors in silicon have been investigated under the high resolution of a Fourier-transform spectrometer. Using a "strain-free" mounting technique, the linewidths are observed to be much narrower than those reported earlier in the literature; the observed linewidths appear to be limited by the "lifetime" effects. The linewidths and shapes of the excitation lines of phosphorus donors in silicon, introduced by the nuclear transmutation of ${}_{}{}^{30}{}_{}{}^{}\mathrm{Si}$ into ${}_{}{}^{31}{}_{}{}^{}\mathrm{P}$ by the capture of a slow neutron followed by a ${\beta }^{-}$ decay, are studied; the influence of the charged defects produced by neutron irradiation is demonstrated and explained in terms of the electric fields due to charged impurities and defects.