MESOSCOPIC PHENOMENA IN A-SI BASED MICROSTRUCTURES

The transverse hopping conductivity has been investigated in microstru ctures fabricated on a small-area (micrometer and submicrometer featur e size) thin amorphous Si layer (L = 200 to 440 Angstrom). We have rev ealed sample-to-sample fluctuations of the conductivity, two-level spo ntaneous switching of the hopping current by an amount of 0.5 to 100% dependent on the feature size of the device. Field- and light-induced current fluctuations have been found. The spectral power density of th e random switching can be fitted by a Lorentzian from which effective switching rates can be deduced. They are thermally activated and exhib it a dependence on the voltage applied to the sample and light illumin ation. The results are explained by carrier transport via 1D chains of localized states with spontaneous, field- and light-induced rearrange ment of the atomic structure of the material.