Mechanism of flicker noise in a-Si:H thin films

Flicker noise in n-type hydrogenated amorphous silicon is studied from room temperature to about 420 K. The device is first annealed at 450 K and subsequently cooled at rates of 0.5 K/s or 0.02 K/s. The temperature variations of both the voltage noise power spectra and the conductivity of the material exhibit strong dependencies on the cooling rate of the device. The current dependence of the voltage noise power spectra is found to deviate from the power law indicating that the noise arises from a non-linear system. The voltage noise power spectra is found to vary as R/sup P/ and p is dependent on the temperature and the cooling process of the device. Our experimental data provides strong evidence that the flicker noise originates from hydrogen motion within the material. The process appears to cause fluctuations in the device conductance by modulating the percolation path of the carriers.