A Monte Carlo Analysis of Diffusion-Noise Properties in GaAs-AlGaAs Quantum Wells

We present a general analysis of steady-state velocity fluctuations, diffusion and noise for electrons in GaAs-AlGaAs quantum wells under high-field conditions using an Ensemble Monte Carlo simulation. Here we analyze for the first time diffusivity and noise problems in a two-dimensional structure by means of the velocity autocorrelation function. From the Monte Carlo simulation we obtain results for the diffusion coefficient at various field strengths and for the autocorrelation function of velocity fluctuations as a function of time for different physical conditions. We also show the power spectral density of velocity fluctuations as a function of frequency for such systems, and a comparison is made with the available data in the literature. The role of interband scattering, a new noise source not present in bulk structures, is discussed, together with the comparison between bulk and 2D results.