Microscopic origin of light emission in Al_yGa_{1-y}N/GaN superlattice: Band profile and active site

TL;DR

This study uses first-principles calculations to uncover the microscopic origin of light emission in AlGaN/GaN superlattices, highlighting the role of local polarization and active sites in the quantum well.

Contribution

It provides a detailed microscopic understanding of light emission mechanisms in AlGaN/GaN superlattices, emphasizing the influence of local polarization and active site positioning.

Findings

Active site at zero local polarization causes main band-edge emission.

Charge injection results in broadening of the band gap and blueshift of emission.

Local polarization effects are crucial for understanding emission properties.

Abstract

We present first-principles calculations of AlGaN/GaN superlattice, clarifying the microscopic origin of the light emission and revealing the effect of local polarization within the quantum well. Profile of energy band and distributions of electrons and holes demonstrate the existence of a main active site in the well responsible for the main band-edge light emission. This site appears at the position where the local polarization becomes zero. With charge injection, the calculated optical spectra show that the broadening of the band gap at the active site leads to the blueshift of emission wavelength.