Long-range disorder and the Staebler-Wronski effect in N-type amorphous silicon

Experimental measurements of the Q function (a comparison of the dark conductivity and thermopower activation energies) as a function of light exposure are reported for a variety of n-type-doped hydrogenated amorphous silicon films. The samples studied represent a wide range of deposition conditions, including variations of the deposition temperature, the rf power during deposition, and the doping ratio of phosphorus to silicon. The Q function of these films is measured before and after light-induced defect creation. No significant change in the Q function was observed after light-induced defect creation for any of these samples, consistent with no light-induced change in the long-range disorder at the conduction-band mobility edge. Measurements of the non-Gaussian statistics which characterize the conductance fluctuations (1/f noise) are also found to remain unchanged following light exposure.