Conductivity and noise in thin films of nonhydrogenated amorphous silicon in the hopping regime

Excess noise measurements have been carried out in nonhydrogenated amorphous silicon material at room temperature. The temperature dependence of the conductivity has shown that, at room temperature, noise measurements deal with transport mechanisms dominated by hopping to nearest neighbors. At lower temperature there is variable range hopping from which the number of states near the Fermi level was determined. The ohmic behavior of structures such as molybdenum-amorphous silicon-molybdenum, and the V² dependence of the noise spectral density indicate that $\text{1}\text{f}$ noise is characteristic for this material. A simple theory of phonon assisted hopping $\text{1}\text{f}$ noise is presented. From this the fluctuations. Some preliminary data are shown for hydrogenated amorphous silicon. The noise shows a Lorentzian, indicative of generation-recombination noise.