Influence of deposition conditions on long-range electronic disorder in n-type doped hydrogenated amorphous silicon

Measurements of the conductivity, thermopower, and infrared absorption for n-type doped hydrogenated amorphous silicon (Formula presented) films grown under varying deposition conditions have been performed, in order to test the role that compositional fluctuations associated with the bonded hydrogen microstructure have on the long-range disorder present at the conduction-band edge. Films grown either with high deposition power or at low substrate temperature have a lower conductivity and more long-range disorder of the mobility edge, as measured by the difference in the activation energies of the conductivity and thermopower. The long-range disorder (measured by the activation energy difference) is larger for films with a larger fraction of (Formula presented) bonds, as inferred from the infrared absorption, indicating that the hydrogen bonding is related to long-range electronic disorder. Computer simulations have also been performed in order to test the proposal that long-range disorder is responsible for the difference in the conductivity and thermopower activation energies.