Interband polarized absorption in InP polytypic superlattices

TL;DR

This paper provides a theoretical analysis of how crystal phase mixing and quantum confinement influence interband absorption and light polarization in InP polytypic superlattices, matching experimental optical trends.

Contribution

It introduces a comprehensive model combining crystal phase effects, quantum confinement, and optical confinement to explain polarization behavior in InP superlattices.

Findings

High sensitivity of polarization to zinc-blende concentration.

Quantum confinement reduces polarization sensitivity.

The model matches recent experimental photoluminescence data.

Abstract

Recent advances in growth techniques have allowed the fabrication of semiconductor nanostructures with mixed wurtzite/zinc-blende crystal phases. Although the optical characterization of these polytypic structures is well eported in the literature, a deeper theoretical understanding of how crystal phase mixing and quantum confinement change the output linear light polarization is still needed. In this paper, we theoretically investigate the mixing effects of wurtzite and zinc-blende phases on the interband absorption and in the degree of light polarization of an InP polytypic superlattice. We use a single 8$\times$8 k$\cdot$p Hamiltonian that describes both crystal phases. Quantum confinement is investigated by changing the size of the polytypic unit cell. We also include the optical confinement effect due to the dielectric mismatch between the superlattice and the vaccum and we show it to be necessary to match experimental results. Our calculations for large wurtzite concentrations and small quantum confinement explain the optical trends of recent photoluminescence excitation measurements. Furthermore, we find a high sensitivity to zinc-blende concentrations in the degree of linear polarization. This sensitivity can be reduced by increasing quantum confinement. In conclusion, our theoretical analysis provides an explanation for optical trends in InP polytypic superlattices, and shows that the interplay of crystal phase mixing and quantum confinement is an area worth exploring for light polarization engineering.