2. Articole

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    AERO-Ga2O3 NANOMATERIAL ELECTROMAGNETICALLY TRANSPARENT FROM MICROWAVES TO TERAHERTZ FOR INTERNET OF THINGS APPLICATIONS
    (2020) Braniște, Tudor; Dragoman, Mircea; Jucov, Serghei; Aldrigo, Martino; Ciobanu, Vladimir; Iordănescu, Sergiu; Alîabîeva, Liudmila; Fumagalli, Francesco; Ceccone, Giacomo; Raevschi, Simion; Schűtt, Fabian; Adelung, Rainer; Colpo, Pascal; Gorșunov, Boris; Tighineanu, Ion
    In this paper, fabrication of a new material is reported, the so-called Aero-Ga2O3 or Aerogallox, which represents an ultra-porous and ultra-lightweight three-dimensional architecture made from interconnected microtubes of gallium oxide with nanometer thin walls. The material is fabricated using epitaxial growth of an ultrathin layer of gallium nitride on zinc oxide microtetrapods fabricated using epitaxial growth of an ultrathin layer of gallium nitride on zinc oxide microtetrapods followed by decomposition of sacrificial ZnO and oxidation of GaN which according to the results of X-ray diffraction (XRD) and X-ray photoemission spectroscopy (XPS) characterizations, is transformed gradually in β-Ga2O3 with almost stoichiometric composition. The investigations show that the developed ultra-porous Aerogallox exhibits extremely low reflectivity and high transmissivity in an ultrabroadband electromagnetic spectrum ranging from X-band (8–12 GHz) to several terahertz which opens possibilities for quite new applications of gallium oxide, previously not anticipated.
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    ELECTROMAGNETIC INTERFERENCE SHIELDING IN X-BAND WITH AERO-GaN
    (IOP Publishing Ltd, 2019) Raevschi, Simion; Dragoman, Mircea; Braniste, Tudor; Iordanescu, Sergiu; Aldrigo, Martino; Shree, Sindu; Adelung, Rainer; Tiginyanu, Ion
    We investigate the electromagnetic shielding properties of an ultra-porous lightweight nanomaterial named aerogalnite (aero-GaN). Aero-GaN is made up of randomly arranged hollow GaN microtetrapods, which are obtained by direct growth using hydride vapor phase epitaxy of GaN on the sacrificial network of ZnO microtetrapods. A 2 mm thick aero-GaN sample exhibits electromagnetic shielding properties in the X-band similar to solid structures based on metal foams or carbon nanomaterials. Aero-GaN has a weight four to five orders of magnitude lower than the weight of metals.
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    TERAHERTZ SHIELDING PROPERTIES OF AERO-GaN
    (IOP Publishing Ltd, 2019) Braniste, Tudor; Dragoman, Mircea; Alyabyeva, Liudmila; Zhukov, Sergey; Ciobanu, Vladimir; Aldrigo, Martino; Raevschi, Simion; Dragoman, Daniela; Iordanescu, Sergiu; Shree, Sindu; Gorshunov, Boris; Adelung, Rainer; Tiginyanu, Ion
    The electrodynamic properties of the first aero-material based on compound semiconductor namely of Aero-GaN, in the terahertz frequency region are experimentally investigated. Spectra of complex dielectric permittivity, refractive index, surface impedance are measured at frequencies 4–100 cm−1 and in the temperature interval 4–300 K. The shielding properties are found based on experimental data. The aero-material shows excellent shielding effectiveness in the frequency range from 0.1 to 1.3 THz, exceeding 40 dB in a huge frequency bandwidth, which is of high interest for industrial applications. These results place the aero-GaN among the best THz shielding materials known today.