6 kW/cm² UVC laser threshold in optically pumped lasers achieved by controlling point defect formation

Abstract

Optically pumped lasing from AlGaN/AlN multiple quantum wells grown on single-crystalline AlN substrates with lasing thresholds as low as 6 kW/cm2 is demonstrated via the reduction of unintentional point defects in the active region and waveguide, which reduces the non-radiative recombination by 2 orders of magnitude. A higher lasing threshold of 11 kW/cm2 is observed for AlGaN barriers, owing to the reduced localization of electrons and holes in the wells. It is shown that for electrically injected UVC laser diodes, AlGaN barriers are essential.

Optical Quality and Stimulated Emission of Molecular Beam Epitaxy Grown AlGaN in the Deep Ultraviolet

“…[9][10][11] In contrast, however, the development of AlGaN-based deep UV lasers is much slower, and the majority studies focus on optically pumped AlGaN QW lasers. [12][13][14][15][16][17] It is not until very recently that the electrically pumped AlGaN QW deep UV laser operating at 271.8 nm was achieved, [18] after the clamping of the lasing wavelength at 336 nm for more than one decade. [19,20] Different from MOCVD, molecular beam epitaxy (MBE) offers ultra-high vacuum environment that could minimize impurity incorporation, as well as separate controls on the substrate and source temperatures and lower growth rate, which can provide excellent control on the heterointerface properties.…”

“…[ 9–11 ] In contrast, however, the development of AlGaN‐based deep UV lasers is much slower, and the majority studies focus on optically pumped AlGaN QW lasers. [ 12–17 ] It is not until very recently that the electrically pumped AlGaN QW deep UV laser operating at 271.8 nm was achieved, [ 18 ] after the clamping of the lasing wavelength at 336 nm for more than one decade. [ 19,20 ]…”

Sec‐Eliminating the SARS‐CoV‐2 by AlGaN Based High Power Deep Ultraviolet Light Source

“…It is worth noting that such an outstanding AlN/NSPP template does not merely contribute to the UVC‐LED, but also is promising for other types of nitrides‐based devices such as UV detectors and power devices. [ 29–34 ] Atomic force microscopy (AFM) image shown in Figure a reveals a typical step‐bunching morphology of the smooth as‐grown AlN surface on NPSS. Such step‐bunching morphology is typically observed in AlN grown on both flat sapphire substrates and NPSSs, which is caused by the relatively high Al adatom diffusion length due to high growth temperature for AlN (usually above 1150 °C).…”

Influence of the Growth Substrate on the Internal Quantum Efficiency of AlGaN/AlN Multiple Quantum Wells Governed by Carrier Localization

“…The growth of AlN barriers was intended to improve carrier confinement and to minimize thermal escape. [5,6] Finally, a 50 nm thick AlN capping layer was grown to reduce carrier surface effects such as band banding due to Fermi level pinning. [7] Both samples were deposited under identical growth conditions (V/III ratios, growth temperature, etc.)…”