Optical polarization anisotropy, intrinsic Stark effect and Coulomb effects on the lasing characteristics of [0001]-oriented GaN/Al0.3Ga0.7N quantum wells

TL;DR

This paper provides a theoretical analysis of optical properties and effects in [0001]-oriented GaN/Al0.3Ga0.7N quantum wells, revealing how electric fields, Coulomb interactions, and well width influence lasing characteristics in the ultraviolet spectrum.

Contribution

It introduces a self-consistent model for electron-hole distributions and optical gain in GaN/AlGaN quantum wells, highlighting the impact of electric fields and Coulomb effects on lasing properties.

Findings

Optical gain has strict x/y polarization.

Wider wells show a blueshift of gain maximum with plasma density.

Strong Coulomb enhancement affects the optical properties.

Abstract

We present a theoretical investigation of space separated electron and hole distributions, which consists in the self-consistent solving of the Schrodinger equations for electrons and holes and the Poisson equation. The results are illustrated for the GaN/Al0.3Ga0.7N quantum well. The optical gain spectrum in a [0001]-oriented GaN/Al0.3Ga0.7N quantum well in the ultraviolet region is calculated. It is found that both the matrix elements of optical transitions from the heavy hole band and the optical gain spectrum have only the strict x (or y) light polarization. We present studies of the influence of the confinement of wave functions on the optical gain which implicitly depends on the built-in electric field calculated to be 2.3 MV/cm. Whereas the structures with narrow well widths exhibit the usual development of the light gain maximum almost without shifting the spectral region, a significant blueshift of the gain maximum is found with increase in the plasma density for wider quantum wells. This blueshift is ascribed to the interplay between the screening of a strain-induced piezoelectric field and the bandstructure. A large Sommerfeld or Coulomb enhancement is present in the quantum well.