Anomalous hopping in hydrogenated amorphous silicon doped with phosphine

Temperature dependent conductivity measurements were performed on phosphine doped hydrogenated amorphous silicon grown by plasma enhanced chemical vapor deposition over a range of argon dilution and phosphine [PH3] doping. Resistance curve derivative analysis was used along with hopping conductivity modeling to determine the nature of the conduction mechanism. The results of this analysis show that anomalous hopping conduction, where lnσ∝T−p with p≈0.75, describes the temperature dependent conductivity of most of the samples studied, and represents the first observation of anomalous conduction in phosphine doped amorphous silicon. Argon dilution modifies the efficiency of dopant incorporation into electrically active sites, and the resultant defects within the silicon network appear to sufficiently modify the density of states, leading to anomalous conduction. Raman spectroscopy was used as additional evidence of these structural changes.