ENSEMBLE MONTE-CARLO WITH POISSON SOLVER FOR THE STUDY OF CURRENT FLUCTUATIONS IN HOMOGENEOUS GAAS STRUCTURES

An analysis of current fluctuations in homogeneous N-type GaAs structures of different lengths and doping concentrations is presented. The study is performed coupling self-consistently a Poisson solver to a many-particle Monte Carlo simulation. The autocorrelation functions and the spectral density of current fluctuations are calculated, dividing them into different contributions that allow one to analyze several sources of noise. A qualitative analysis of shot noise is made. Different behaviors of current fluctuations are found among the different structures; these are interpreted in terms of the microscopic processes occurring inside them. For high values of impurity concentration (10(17) CM-3), the coupling between fluctuations in the electric field and in carrier velocity is found to be an important source of noise.