Electronic states in heterostructures formed by ultranarrow layers

TL;DR

This paper theoretically investigates electronic states in heterostructures with ultranarrow layers, modeling their effects via transfer matrix parameters to understand localized states, spectra, and absorption properties.

Contribution

It introduces a transfer matrix approach with phenomenological parameters to describe ultranarrow layers' effects on electronic states in heterostructures.

Findings

Localized state binding energies are determined by transfer matrix parameters.

Spectral absorption depends strongly on ultranarrow layer characteristics.

The transfer matrix parameters can be verified through absorption spectra.

Abstract

Low-energy electronic states in heterosrtuctures formed by ultranarrow layer (single or several monolayers thickness) are studied theoretically. The host material is described within the effective mass approximation and effect of ultranarrow layers is taken into account within the framework of the transfer matrix approach. Using the current conservation requirement and the inversion symmetry of ultranarrow layer, the transfer matrix is written through two phenomenological parameters. The binding energy of localized state, the reflection (transmission) coefficient for the single ultranarrow layer case, and the energy spectrum of superlattice are determined by these parameters. Spectral dependency of absorption in superlattice due to photoexcitation of electrons from localized states into minibands is strongly dependent on the ultranarrow layers characteristics. Such a dependency can be used for verification of the transfer matrix parameters.