Conductance fluctuations in doped hydrogenated amorphous silicon

Conductance fluctuations in n-type doped hydrogenated amorphous silicon (a-Si:H) films are described. The spectral density of the coplanar current fluctuations has a 1/f frequency dependence for frequency f from 1f${10}^4$ Hz over the temperature range 300T${10}^{\mathrm{-}6}$ to ${10}^{\mathrm{-}7}$ ${\mathrm{cm}}^3$ with fluctuations as large as ΔR/R∼1%. Statistical analysis of these fluctuations indicates that the 1/f noise is strongly non-Gaussian, suggestive of cooperative interactions between fluctuators. A model is proposed in which the noise is dominated by inhomogeneous current paths whose local conductivity is modulated by bonding rearrangements enabled by hydrogen motion.