Investigation of 1/f noise sources with the coherence function

We demonstrate the application of the coherence function to analyze the 1/f noise sources in a planar semiconductor structure with multiple electrical contacts. This article includes noise and coherence function measurements, the 1/f noise model for the transmission-line-model (TLM) sample, theoretical calculations of the coherence function, and a comparison of theoretical and experimental values. In the developed noise model, bulk semiconductor noise and metal-semiconductor contact noise are considered noise sources. It was shown that the experimental results of coherence measurements are well explained by the model, which assumes 1/f noise from contacts and no 1/f noise from a bulk semiconductor. The presented method can be used to find dominant noise sources originating from bulk semiconductor or metal-semiconductor contacts in planar structures. The strength of the method, in comparison with models based only on power spectral density, is straightforward interpretation and the lack of sophisticated model parameters.