Efficient, mercury-free deep ultraviolet (DUV) light-emitting diodes (LEDs) are becoming a crucial challenge for many applications such as water purification. For decades, the poor p-type doping and difficult current injection of Al-rich AlGaN-based DUV LEDs have limited their efficiency and therefore their use. We present here the significant increase in AlN p-doping thanks to Mg/In codoping, which leads to an order of magnitude higher Mg solubility limit in AlN nanowires (NWs). Optimal electrical activation of acceptor impurities has been further achieved by electron irradiation, resulting in tunnel conduction through the AlN NW p-n junction. The proposed theoretical scenario to account for enhanced Mg incorporation involves an easy ionization of In-vacancy complex associated with a negative charging of Mg in In vicinity. This leads to favored incorporation of negatively charged Mg into the AlN matrix, opening the path to the realization of highly efficient NW-based LEDs in the DUV range.
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http://dx.doi.org/10.1021/acs.nanolett.9b01394 | DOI Listing |
ACS Appl Mater Interfaces
October 2024
Department of Mathematics and Natural Science, Institute for Physics, Fundamentals of Energy Materials, Ilmenau University of Technology, Ilmenau 98693, Germany.
Functional and abundant substrate materials are relevant for applying all sophisticated semiconductor-based device components such as nanowire arrays. In the case of GaN nanowires grown by metalorganic vapor phase epitaxy, Si(111) substrates are widely used, together with an AlN interlayer to suppress the well-known Ga-based melt-back-etching. However, the AlN interlayer can degrade the interfacial conductivity of the Si(111) substrate.
View Article and Find Full Text PDFPolymers (Basel)
November 2023
School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China.
With the miniaturization of current electronic products, ceramic/polymer composites with excellent thermal conductivity have become of increasing interest. Traditionally, higher filler fractions are required to obtain a high thermal conductivity, but this leads to a decrease in the mechanical properties of the composites and increases the cost. In this study, silicon nitride nanowires (SiNNWs) with high aspect ratios were successfully prepared by a modified carbothermal reduction method, which was further combined with AlN particles to prepare the epoxy-based composites.
View Article and Find Full Text PDFAdv Mater
November 2023
Key Laboratory of Mesoscopic Chemistry of MOE and Jiangsu Provincial Laboratory for Nanotechnology, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023, China.
Lithium-selenium batteries are characterized by high volumetric capacity comparable to Li-S batteries, while ≈10 times higher electrical conductivity of Se than S is favorable for high-rate capability. However, they also suffer from the "shuttling effect" of lithium polyselenides (LPSes) and Li dendrite growth. Herein, a multifunctional Janus separator is designed by coating hierarchical nitrogen-doped carbon nanocages (hNCNC) and AlN nanowires on two sides of commercial polypropylene (PP) separator to overcome these hindrances.
View Article and Find Full Text PDFNanotechnology
September 2023
Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e.V., Hausvogteiplatz 5-7, D-10117 Berlin, Germany.
We study the molecular beam epitaxy of AlN nanowires between 950 °C and 1215 °C, well above the usual growth temperatures, to identify optimal growth conditions. The nanowires are grown by self-assembly on TiN(111) films sputtered onto AlO. Above 1100 °C, the TiN film is seen to undergo grain growth and its surface exhibits {111} facets where AlN nucleation preferentially occurs.
View Article and Find Full Text PDFNanoscale Adv
May 2023
Department of Engineering, University of Cambridge 9 JJ Thomson Ave Cambridge CB3 0FA UK
Understanding the growth mechanisms of III-nitride nanowires is of great importance to realise their full potential. We present a systematic study of silane-assisted GaN nanowire growth on -sapphire substrates by investigating the surface evolution of the sapphire substrates during the high temperature annealing, nitridation and nucleation steps, and the growth of GaN nanowires. The nucleation step - which transforms the AlN layer formed during the nitridation step to AlGaN - is critical for subsequent silane-assisted GaN nanowire growth.
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