Random telegraph-switching noise in coplanar current measurements of amorphous silicon

Resistance fluctuations are reported for n-type doped hydrogenated amorphous silicon (a-Si:H) using a coplanar electrode configuration with effective sample volumes of ${10}^{\mathrm{-}6–}$ ${10}^{\mathrm{-}7}$ ${\mathrm{cm}}^3$. Random telegraph-switching noise is observed with fluctuations as large as δR/R∼${10}^{\mathrm{-}2}$ for the temperature range 350<T<425 K. Comparison of two-probe and four-probe measurements confirms that these results are not due to contact noise. The switching noise may result from inhomogeneous current paths arising from the hydrogen microstructure in the a-Si:H which change their resistance value as hydrogen atoms hop from one bonding configuration to another.