Long-range fluctuations of random potential landscape as a mechanism of 1/f noise in hydrogenated amorphous silicon

We describe a mechanism, which links the long-range potential fluctuations induced by charged defects to the low frequency resistance noise widely known as 1/f noise. This mechanism is amenable to the first principles microscopic calculation of the noise spectrum, which includes the absolute noise intensity. We have performed such a calculation for the thin films of hydrogenated amorphous silicon (a-Si:H) under the condition that current flows perpendicular to the plane of the films, and found a very good agreement between the theoretical noise intensity and the measured one. The mechanism described is quite general. It should be present in a broad class of systems containing poorly screened charged defects.