Permutations of the transverse momentum dependent effective valence-band potential for layered heterostructures. Pseudomorphic strain effects

TL;DR

This paper investigates how the effective valence-band potential profile for holes in layered heterostructures evolves under strain and band mixing, revealing complex permutations and strain effects that impact heterostructure design.

Contribution

It introduces a detailed analysis of $V_{eff}$ permutations for holes under strain and band mixing, a novel aspect not previously addressed in transport or theoretical studies.

Findings

Permutation of $V_{eff}$ resembles a 'keyboard' pattern.

Strain can suppress or induce $V_{eff}$ permutations.

Multiband-mixing and stress effects compete and cannot be neglected.

Abstract

The evolution of transverse-momentum-dependent effective band offset ($V_{\mathrm{eff}}$) profile for heavy (\emph{hh})- and light-holes (\emph{lh}), is detailed studied. Several new features in the metamorphosis of the standardized fixed-height $V_{\mathrm{eff}}$ profile for holes, in the presence of gradually increasing valence-band mixing and pseudomorphic strain, are presented. In some $III-V$ unstrained semiconducting layered heterostructures a fixed-height potential, is not longer valid for \emph{lh}. Indeed, we found ---as predicted for electrons---, permutations of the $V_{\mathrm{eff}}$ character for \emph{lh}, that resemble a "\emph{keyboard}", together with bandgap changes, whenever the valence-band mixing varies from low to large intensity. Strain is able to diminish the \emph{keyboard} effect on $V_{\mathrm{eff}}$, and also makes it emerge or vanish occasionally. We found that multiband-mixing effects and stress induced events, are competitors mechanisms that can not be universally neglected by assuming a fixed-height rectangular spatial distribution for fixed-character potential energy, as a reliable test-run input for heterostructures. Prior to the present report, neither direct transport-domain measurements, nor theoretical calculations addressed to these $V_{\mathrm{eff}}$ evolutions and permutations, has been reported for holes, as far as we know. Our results may be of relevance for promising heterostructure's design guided by valence-band structure modeling to enhance the hole mobility in $III-V$ materials.