High efficiency deep-UV emission at 219 nm from ultrathin MBE GaN/AlN quantum heterostructures

TL;DR

This paper demonstrates that ultrathin GaN quantum disks embedded in AlN can produce efficient deep-UV emission at 219 nm, surpassing traditional alloy quantum wells in efficiency and wavelength control.

Contribution

It introduces high-quality epitaxial GaN/AlN heterostructures with extreme quantum confinement for deep-UV emission, offering a new approach over alloy quantum wells.

Findings

Achieved 40% internal quantum efficiency at 219 nm

Demonstrated deep-UV emission far above GaN bulk bandgap

Engineered optical properties for controlled photon emission

Abstract

Deep ultraviolet (UV) optical emission below 250 nm (~5 eV) in semiconductors is traditionally obtained from high aluminum containing AlGaN alloy quantum wells. It is shown here that high-quality epitaxial ultrathin binary GaN quantum disks embedded in an AlN matrix can produce efficient optical emission in the 219-235 nm (~5.7 to 5.3 eV) spectral range, far above the bulk bandgap (3.4 eV) of GaN. The quantum confinement energy in these heterostructures is larger than the bandgaps of traditional semiconductors, made possible by the large band offsets. These MBE-grown extreme quantum-confinement GaN/AlN heterostructures exhibit internal quantum efficiency as high as 40% at wavelengths as short as 219 nm. These observations, together with the ability to engineer the interband optical matrix elements to control the direction of photon emission in such new binary quantum disk active regions offers unique advantages over alloy AlGaN quantum well counterparts for the realization of deep-UV light-emitting diodes and lasers.