Oscillatory screening of the dc electric field in the Si-SiO$_2$ multiple quantum wells probed by second-harmonic generation

TL;DR

This study reveals that the DC electric field in Si-SiO$_2$ multiple quantum wells exhibits an oscillatory decay pattern, contrasting with the typical monotonic decay in 3D semiconductors, as observed through second-harmonic generation.

Contribution

The paper introduces a model accounting for localized electrons, Coulomb interactions, and anisotropic effective mass to explain the oscillatory screening of electric fields in quantum wells.

Findings

Oscillatory decay of the DC electric field in quantum wells

Model incorporating Coulomb interaction and anisotropy explains the phenomenon

Deviation from classical 3D Fermi liquid behavior

Abstract

DC-electric field, being screened in 3D semiconductors, normally decays monotonically in space. Experimental studies of the DC electric field screening in Si-SiO$_2$ multiple quantum wells by electric field induced optical second-harmonic generation show a non-monotonic, oscillatory-like decay. The model of electrons localized inside quantum wells, with the first subband occupied, allows a description of the phenomenon. Interwell Coulomb interaction, a finite value of the electron charge and strong effective-mass anisotropy result in a crucial difference from 3D Fermi liquid.