Fast photoluminescence decay ina-Si:H

Photoluminescence (PL) decay in a-Si:H has been measured in the 0.1- to 50-ns range, and the dependence upon temperature, emission energy, excitation energy, and electric field has been systematically investigated. A fast analog technique with a time resolution of 100 ps was used for the measurements. We present a method for quantitatively characterizing the PL decay in terms of a model function, with which the experimental time broadening is removed by deconvolution. The model function is I(t)=${\mathit{a}}_0$+${\mathit{tsum}}_{\mathit{i}=1\mathrm{}}^{\mathit{n}}$ ${\mathit{a}}_{\mathit{i}}$exp(-t/${\mathrm{\tau }}_{\mathit{i}}$), where ${\mathit{a}}_0$, ${\mathit{a}}_{\mathit{i}}$, and ${\mathrm{\tau }}_{\mathit{i}}$ are the fitting parameters. These fits yield three distinct lifetimes: ${\mathrm{\tau }}_1$=0.8±0.2 ns, ${\mathrm{\tau }}_2$=3.8±0.5 ns, and ${\mathrm{\tau }}_3$=18.0±3.0 ns. The variation of these three lifetimes as a function of temperature, emission energy, excitation energy, and eletric field is studied and the results are interpreted in terms of bound-exciton recombination.