# In-plane spectrum in superlattices

## TL;DR

This paper identifies inaccuracies in the traditional theory of superlattice in-plane spectra at small momentum and introduces a modified model that aligns better with experimental magneto-absorption data.

## Contribution

The authors develop a new theoretical approach that relates the in-plane spectrum and effective masses to the superlattice's effective bandgap, improving prediction accuracy.

## Key findings

- Traditional theory overestimates the parabolic region energy range.
- Modified theory matches experimental magneto-absorption results.
- Effective masses are determined by the superlattice's effective bandgap.

## Abstract

We show that the existing theory does not give correct in-plane spectrum of superlattices at small in-plane momentum. Magneto-absorption experiments demonstrate that the energy range of the parabolic region of the spectrum near the electron subband bottom is by the order of magnitude lower than the value predicted by the traditional approach. We developed a modified theory according to which the energy range of the parabolic region and carrier in-plane effective masses are determined by the effective bandgap of the superlattice rather than by the bulk bandgaps of the superlattice layers. The results of the new theory are consistent with the experiment.