Voltage noises with power spectra of the form 1/f were studied in a series of custom and commercial p-channel metal-oxide-semiconductor field-effect transistors. Detailed measurements of the time-correlation functions indicated that the noise originated from a stationary and Gaussian source. The spatial correlation function, measured in devices made with extra voltage probes placed in the conduction channels, showed no measurable amount of correlation down to a distance of 7 m, excluding the possibility of a diffusion mechanism for the noise. The results, combined with the experimental data on the dependence of the noise power spectra on the bias conditions, led us to establish a simple model based on a variation of the McWhorter model to account for the noise. Built into the model was an energy dependence of the trap concentration which in turn yielded a spatial dependence in the presence of a gate bias. This model explained quantitatively the experimentally observed change in the exponent of the noise spectrum as the gate bias was varied. It was then meaningful to compare the experimental and computed noise powers at a single, fixed frequency.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics