Positron diffusion was investigated in hydrogenated amorphous silicon using positron beam timing spectroscopy. The measurement of the rate of emission of annihilation photons as a function of the time interval between annihilation and incoming pulse of positrons, allowed the measurement of positron lifetime spectrum at different depths. The results indicated that the dominant positron state in a particular covalent random network was a localized state located at hydrogen terminated dangling bond defects. Hopping diffusion of positrons was observed and the migration enthalpy for positrons in that state was found to be 17.7(3) meV.    «

Positron diffusion was investigated in hydrogenated amorphous silicon using positron beam timing spectroscopy. The measurement of the rate of emission of annihilation photons as a function of the time interval between annihilation and incoming pulse of positrons, allowed the measurement of positron lifetime spectrum at different depths. The results indicated that the dominant positron state in a particular covalent random network was a localized state located at hydrogen terminated dangling bond...    »