Influence of excitonic effects on luminescence quantum yield in silicon
  Nonradiative exciton lifetime in silicon is determined by comparison of the experimental and theoretical curves of bulk minority charge carriers lifetime on doping and excitation levels. This value is used to analyze the influence of excitonic effects on internal luminescence quantum yield at room temperature, taking into account both nonradiative and radiative exciton lifetimes. A range of Shockley-Hall-Reed lifetimes is found, where excitonic effects lead to an increase of internal luminescence quantum yield. 
A.V. Sachenko, V.P. Kostylyov, V.M. Vlasyuk, I.O. Sokolovskyi and M.   Evstigneev
cond-mat.mtrl-sci