Magnetic field effect on the optoelectronic response of amorphous hydrogenated silicon.

We have studied the magneto-photoluminescence and magneto photoconductivity in amorphous hydrogenated silicon (a-Si:H) thin films and devices as a function of temperature up to field of 5 Tesla. The magnetic field effects (MFE) are interpreted as spin mixing between spin-singlet and spin-triplet charge pairs due to the "delta-$g$" mechanism that is based on the $g$-value difference between the paired electron and hole, which directly affects the rate of radiative recombination and charge carrier separation, respectively. We found that the MFE($B)$ response does not form a Lorentzian (that is expected from the "delta-$g$" mechanism) due to disorder in the film that results in a broad distribution of e-h recombination rates, which could be extracted directly by time-resolved photoluminescence.