Assessment of AlGaN/AlN superlattices on GaN nanowires as active region of electron-pumped ultraviolet sources

Abstract

In this paper, we describe the design and characterization of 400-nm-long (88 periods) AlxGa1-xN/AlN (0 < x < 0.1) quantum dot superlattices deposited on self-assembled GaN nanowires for application in electron-pumped ultraviolet sources. The optical performance of GaN/AlN superlattices on nanowires is compared with the emission of planar GaN/AlN superlattices with the same periodicity and thickness grown on bulk GaN substrates along the N-polar and metal-polar crystallographic axes. The nanowire samples are less sensitive to nonradiative recombination than planar layers, attaining internal quantum efficiencies (IQE) in excess of 60% at room temperature even under low injection conditions. The IQE remains stable for higher excitation power densities, up to 50 kW/cm2. We demonstrate that the nanowire superlattice is long enough to collect the electron-hole pairs generated by an electron beam with an acceleration voltage VA = 5 kV. At such VA, the light emitted from the nanowire ensemble does not show any sign of quenching under constant electron beam excitation (tested for an excitation power density around 8 kW/cm2 over the scale of minutes). Varying the dot/barrier thickness ratio and the Al content in the dots, the nanowire peak emission can be tuned in the range from 340 to 258 nm. Keywords: GaN, AlN, nanowire, ultraviolet

References in corpus (11)

• Single nanowire solar cells beyond the Shockley-Queisser limit
• Nanometer Scale Spectral Imaging of Quantum Emitters in Nanowires and Its Correlation to Their Atomically Resolved Structure
• Carrier Confinement in GaN/AlGaN Nanowire Heterostructures for 0 < x <= 1
• Visualising highly localised luminescence in GaN/AlN heterostructures in nanowires
• Alloy inhomogeneity and carrier localization in AlGaN sections and AlGaN/AlN nanodisks in nanowires with 240-350 nm emission
• Nanowire photodetectors based on wurtzite semiconductor heterostructures
• Compatibility of the selective area growth of GaN nanowires on AlN-buffered Si substrates with the operation of light emitting diodes
• Electrical and Optical Properties of Heavily Ge-Doped AlGaN
• Effect of doping on the intersubband absorption in Si- and Ge-doped GaN/AlN heterostructures
• Long-lived excitons in GaN/AlN nanowire heterostructures
• Quenching of the luminescence intensity of GaN nanowires under electron beam exposure: Impact of C adsorption on the exciton lifetime

Cited by in corpus (4)

• Ultraviolet Photodetectors based on GaN and AlGaN/AlN Nanowire Ensembles: Effects of Planarization with Hydrogen Silsesquioxane and Nanowire Architecture
• Internal quantum efficiency of AlGaN/AlN quantum dot superlattices for electron-pumped ultraviolet sources
• AlGaN/GaN asymmetric graded-index separate confinement heterostructures designed for electron-beam pumped UV lasers
• Decorrelation of internal quantum efficiency and lasing threshold in AlGaN-based separate confinement heterostructures for UV emission