Comment on "Recombination ina-Si: H: Spin-dependent effects"

Street concludes from his recent time-resolved optically detected magnetic resonance (ODMR) data that the enhancing ODMR signals in $a$-Si: H are consistent with a model involving geminate pair recombination at electron and hole tail states, with one spin thermalized, and one unthermalized. We show, firstly, that this model is incompatible with the steady-state ODMR signals in low-defect-density $a$-Si: H; secondly, we note that qualitatively different time-resolved ODMR data have been obtained from two independent ODMR studies, neither of which supports the geminate model; thirdly, we show that the steady-state and time-resolved ODMR data are entirely consistent with the alternative model of nongeminate, distant pair recombination.