On the fluctuation-dissipation of the oxide trapped charge in a MOSFET operated down to deep cryogenic temperatures

TL;DR

This paper investigates oxide trapped charge noise in MOSFETs at deep cryogenic temperatures, deriving new relations and formulas that account for quantum statistical effects beyond classical assumptions.

Contribution

It provides a revised theoretical framework for oxide trapped charge noise in MOSFETs at very low temperatures, incorporating Fermi-Dirac statistics and degenerate effects.

Findings

Established a new relation between oxide trapped charge noise and interface trap conductance at low temperatures.

Developed a formula for 1/f noise that accounts for quantum degeneracy effects.

Showed the inadequacy of the classical Nyquist relation in cryogenic conditions.

Abstract

An analysis of the oxide trapped charge noise in a MOSFET operated down to deep cryogenic temperatures is proposed. To this end, a revisited derivation of the interface trap conductance Gp and oxide trapped charge noise SQt at the SiO2/Si MOS interface is conducted under very low temperature condition, where Fermi-Dirac statistics applies. A new relation between the oxide trapped charge noise SQt and the interface trap conductance Gp is established, showing the inadequacy of the Nyquist relation at very low temperature. Finally, a new formula for the oxide trapped charge 1/f noise, going beyond the classical Boltzmann expression, is developed in terms of oxide trap density and effective temperature accounting for degenerate statistics.