Model calculation of the noise characteristic in double-barrier heterostructures

Using a nonequilibrium Green's-function formalism, we perform model calculations for the current-noise characteristic of a double-barrier heterostructure. A simplified scheme is proposed to include self-consistency between the electronic charge inside the well and the electrostatic potential along the device. We obtain a general expression for the frequency-dependent current fluctuations that reduces to well-known results given by the transmission approach in the zero-frequency limit. Our numerical results are in good agreement with recent experimental data. By means of an approximate calculation, we show that phase coherence has a negligible effect in the noise characteristic of a double-barrier heterostructure.