Influence of doping on transport and recombination of excess charge carriers ina−Si:H

Contactless transient photoconductivity measurements with a time resolution of 0.7 ns have been performed in $a-\mathrm{Si}:\mathrm{H}$ films with different $p$ and $n$ doping levels. An initial fast biomolecular recombination followed by a slow recombination process can be distinguished. Both processes and their relative contribution to the total decay are strongly influenced by the doping level and excitation intensity. A recombination model is proposed which attributes the fast decay to a direct electron-hole recombination and explains the slow-decay regime by a recombination of charge carriers via charged and neutral recombination centers.