A Monte Carlo investigation of plasmonic noise in nanometric n-In_0.53Ga_0.47As channels

By means of numerical simulations we investigate the plasma frequency associated with voltage fluctuations in an n-type In0.53Ga0.47As layer of thickness W and submicron length L embedded in a dielectric medium at T = 300 K. For W = 100 nm and carrier concentrations of 10(16)-10(18) cm(-3) the results are in good agreement with the standard three-dimensional (3D) expression for the plasma frequency. For W <= 10 nm the results exhibit a plasma frequency that depends on L, thus implying that the oscillation mode is dispersive. The corresponding frequency values are in good agreement with the two-dimensional (2D) expression for the plasma frequency obtained for a collisionless regime within the in-plane approximation for the self-consistent electric field. A region of crossover between the 2D and 3D behaviours of the plasma frequency, which we address as an open problem, is evidenced for W > 10 nm. Problems associated with channel lengths shorter than the electron mean free path and the effects of an applied bias will be discussed.