AlGaN/GaN asymmetric graded-index separate confinement heterostructures designed for electron-beam pumped UV lasers

TL;DR

This paper investigates AlGaN/GaN heterostructures with graded-index layers to enhance carrier collection and reduce emission linewidths for UV lasers pumped by electron beams, considering polarization effects.

Contribution

It introduces an asymmetric GRINSCH design that mitigates polarization-induced barriers and improves carrier collection in UV laser heterostructures.

Findings

Carrier collection is significantly improved with the asymmetric GRINSCH.

Graded layers reduce potential barriers caused by polarization.

Strain transition buffers decrease mosaicity and linewidth.

Abstract

We present a study of undoped AlGaN/GaN separate confinement heterostructures designed to operate as electron beam pumped ultraviolet lasers. We discuss the effect of spontaneous and piezoelectric polarization on carrier diffusion, comparing the results of cathodoluminescence with electronic simulations of the band structure and Monte Carlo calculations of the electron trajectories. Carrier collection is significantly improved using an asymmetric graded-index separate confinement heterostructure (GRINSCH). The graded layers avoid potential barriers induced by polarization differences in the heterostructure and serve as strain transition buffers which reduce the mosaicity of the active region and the linewidth of spontaneous emission.