On the theory of time‐resolved band‐tail luminescence in amorphous semiconductors

The time‐dependent moments of a luminescence band due to radiative recombination within electron‐hole pairs localized in band tail states are calculated. Besides the radiative process a competing non‐radiative process by tunneling of the excited electrons (or holes) to defect centres is assumed. The time dependence of the centre of the band ω c ( t ) and the linewidth σ( t ) are shown to be determined by the time evolution of the tail region from which the electrons effectively recombine at t as well as from the time‐dependent electron‐hole separation in the Coulomb interaction. These two mechanisms act in an opposite way and as a result a non‐monotonous behaviour in both ω c ( t ) and σ( t ) observed experimentally is obtained.