Low-frequency noise in a thin active layer α-Si:H thin-film transistors

Low-frequency noise of hydrogenated-amorphous-silicon (α-Si:H) thin-film transistors (TFTs) with a thin active layer and an inverted staggered device structure operating in the conducting mode has been investigated. Pure 1/f-noise spectra were observed. The results show that the physical location of the noise in α-Si:H TFTs is different from that in crystalline metal–oxide–semiconductor field-effect transistors. The noise contributions from the channel and interface have been determined for the device operating in different modes. The 1/f noise of α-Si:H TFTs stems from the channel when the device is operated in the linear region at high gate voltages. However, the 1/f noise of α-Si:H TFTs generated at the interface becomes significant when the device is operated in the saturation region. The interface noise can be explained by the number fluctuation model (ΔN model). The channel noise can be explained by either the ΔN model or the mobility fluctuation model (Δμ model).