Theory of quasi-ballistic FET: steady-state regime and low-frequency noise

We present a theoretical analysis of steady state regimes and low-frequency noise inquasi-ballistic field effect transistors (FETs). The noise analysis is based on the Langevinapproach, which accounts for the microscopic sources of fluctuations originating fromintrachannel electron scattering. The general formulas for local fluctuations of the carrierconcentration, velocity and electrostatic potential, as well as their distributions along thechannel, are found as functions of applied voltage/current. Two circuit regimes with stabilizedcurrent and stabilized voltage are considered. The noise intensities for devices with differentelectron ballisticity in the channel are compared. We suggest that the presented analysis allows abetter comprehension of the physics of electron transport and fluctuations in quasi-ballisticFETs, improves their theoretical description and can be useful for device simulation and design.