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

We present the theoretical analysis of steady state regimes and low-frequency noises in quasi-ballistic FETs. The noise analysis is based on the Langevin approach, which accounts for the microscopic sources of fluctuations originated from intrachannel electron scattering. The general formulas for local fluctuations of the carrier concentration, velocity and electrostatic potential as well, as their distributions along the channel are found as functions of applied voltage/current. Two circuit regimes with stabilized current and stabilized voltage are considered. The noise intensities for the devices with different ballisticity are compared. We suggest that the presented analysis makes better comprehension of physics of electron transport and fluctuations in quasi-ballistic FETs, improves their theoretical description and can be useful for device simulation and design.