STUDY OF 1 F NOISE IN HYDROGENATED AMORPHOUS-SILICON THIN-FILMS/

We report a study of flicker noise in n-type hydrogenated amorphous si licon (a-Si:H) resistive devices from room temperature to about 420 K. The device was first annealed at 450 K and then cooled to room temper ature at a rate of similar to 0.5 K s(-1). The voltage noise power spe ctra and the conductance of the device were characterized from room te mperature to 420 It, The experiment was then repeated with the device annealed again and subsequently cooled at a rate of similar to 0.02 K s(-1). The Arrhenius plots of the voltage noise power spectrum, S-v(S) , are found to exhibit thermal equilibration processes commonly observ ed in a-Si:H materials. Characterization of the bias dependencies of t he noise show that S-v(f) deviates from an I-2 dependence indicating t hat the noise arises from a non-linear process. Also, S-v(f) is propor tional to R-p where p is dependent on the temperature and the cooling process of the device. Our experimental data provide strong evidence t hat the flicker noise originates from hydrogen motion within the mater ial. The process appears to cause fluctuations in the device conductan ce by modulating the percolation path of the carriers. (C) 1997 Elsevi er Science Ltd.