2D MoS2 under switching field conditions: study of high-frequency noise from velocity fluctuations

The transient high-frequency noise response of two-dimensional MoS2 under abrupt large signal switching field conditions is studied by means of an ensemble Monte Carlo simulator. Low-to-high and high-to-low transitions are analyzed at low (77 K) and room temperature, considering several underlying substrates. The incorporation of stochastic individual scattering events allows capturing the transient collective phonon-electron coupling, which is shown to be responsible for the appearance of an oscillatory behaviour in the average velocity and energy at low temperature in the case of MoS2 on SiO2, hBN and Al2O3. Activation and deactivation of surface polar phonon emissions in the low-to-high field switching process yield to the appearance of a relevant peak in the power spectral density of velocity fluctuations in the THz range. The results show the important influence of the substrate type in the noise behaviour of MoS2 at very high frequencies, which is critical for the design of future FET devices based on 2D TMD technology.