Non-Gaussian 1/f noise as a probe of long-range structural and electronic disorder in amorphous silicon

Measurements of the second spectra that characterize the non-Gaussian statistical nature of conductance fluctuations are reported for a series of hydrogenated amorphous silicon thin films. The deposition conditions used to synthesize the films were systematically varied in order to observe the effect that differing amounts of disorder have on the noise statistics. One series of n-type films were deposited at varying substrate temperatures, another n-type series was grown at varying rf powers, and a third series of compensated films was synthesized with varying ratios of phosphine to diborane. None of these series shows any significant change in the non-Gaussian noise statistics as the long-range disorder and deposition properties are changed. Measurements of the second spectra for a film synthesized in an inductively coupled plasma thermal growth system, which yields nano-particles of ∼ 150 nm in diameter, are also reported. These results are discussed in terms of models for the non-Gaussian noise properties in amorphous silicon.