Field-induced generation-recombination noise in (100) n-channel Si-MOSFET's at T = 4.2 K: II. Experiments

The spectral noise intensity of the drain current of an n-channel (100) Si-MOSFET in strong inversion was measured as a function of drain current and gate voltage at T = 4.2 K. In addition to flicker noise and white noise it was possible to distinguish a Lorentzian, which was due to generation-recombination noise. Since, at T = 4.2 K, the 2D-electron gas in the MOSFET in strong inversion is degenerate this generation-recombination noise must be caused by traps in the conduction band. The measured noise relaxation time was found to depend on drain current.Our results can be interpreted in terms of a generation-recombination process in which the generation is partly field-induced. Agreement between theory and experiment is within the experimental error, both for the way in which the inverse noise relaxation time depends on drain current and the way in which the ratio of the low frequency plateau of the spectral noise intensity to the noise relaxation time depends on the product of drain current and drain voltage. Measurements of the ratio of the low-frequency plateau of the spectral noise intensity to the relaxation time versus gate voltage at T = 4.2 K we used to construct an energy spectrum of the density of traps in the conduction band. A maximum is observed at about 14meV above the bottom of the conduction band.