Recombination in amorphous red phosphorus

Radiative recombination in red a-P is reviewed briefly and new experiments on time-resolved photoluminescence are presented. These cover two time ranges: 50 ps-1 ns and 10-200 ns. The results of these experiments are interpreted as indicating that a Coulomb interaction in the ground state can account for the shift of the low-energy luminescence to lower energies with increasing time delay after excitation, which contradicts earlier models. A new model is proposed which attributes the low-energy luminescence to recombination of carriers trapped at P 4 + and P 2 - centres and the high-energy band to recombination of electrons trapped on P 4 + centres with holes in the valence band tail.