@Article{Dimkou_nt_2020,
  author   = {Dimkou, Ioanna and Harikumar, Anjali and Donatini, Fabrice and Lähnemann, Jonas and den Hertog, Martien and Bougerol, Catherine and Bellet-Amalric, Edith and Mollard, Nicolas and Ajay, Akhil and Ledoux, Gilles and Purcell, Stephen T. and Monroy, Eva},
  title    = {Assessment of {AlGaN/AlN} superlattices on {GaN} nanowires as active region of electron-pumped ultraviolet sources},
  journal  = {Nanotechnology},
  year     = {2020},
  volume   = {31},
  number   = {20},
  pages    = {204001},
  month    = feb,
  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},
  arxiv    = {1911.13133 },
  doi      = {10.1088/1361-6528/ab704d},
}