Expulsion of Carriers from the Double-Barrier Quantum Well and Investigation of its Spectral and Transport Consequences

In this work I investigate the expulsion of carriers from nanostructures using the double-barrier quantum well (DBQW) as an example and discuss manifestations of this effect in the spectrum of the DBQW in absence of bias, and in the tunneling current in presence of bias. Assuming equality of the Fermi energy in all regions of the considered system, I compute the relative density of carriers localized in the DBQW and conclude that a fraction of carriers is expelled from this nanostructure. Due to depletion of carriers in the quantum well the DBQW acquires a net electric charge which generates an electrostatic correction to the potential of this nanostructure. I compute the corrections to the energies of the (quasi)stationary states localized in the quantum well and the shifts of the spectral lines corresponding to transitions between those states. Numerical examples illustrate this effect in a wide range of parameters of this system. The electrostatic correction to the potential affects also the probability of tunneling of carriers through the DBQW under bias and contributes a correction to the resonant current in this nanostructure. I compute the tunneling current in the DBQW and conclude that the correction affects the resonant voltage, the magnitude of the current, and the peak-to-valley ratio of the current resonances. I exemplify these effects numerically in a wide range of temperatures, carrier densities, and widths of the quantum well. A proposal of a few methods of experimental verification of the expulsion of carriers and the electrostatic correction to the potential of the DBQW completes this work.