Concentration broadening of bound-exciton spectral lines

We report on an investigation of the broadening of bound exciton (BE) spectral lines at high impurity concentration for shallow acceptors in Si. The broadening is mainly due to the effect of overlapping of wave functions and is calculated by taking account of the dominant binary interaction. The calculated spectral shape for a nondegenerate component in the BE spectra is found to be asymmetric. We find the broadening is strongly dependent on the impurity concentration. The calculated full width at half maximum is about 1 meV for a concentration of 5 × ${10}^{17}$ ${\mathrm{cm}}^{-3\mathrm{}}$ and is less than 0.01 meV for concentrations below 5 × ${10}^{16}$ ${\mathrm{cm}}^{-3\mathrm{}}$.