0000000000034612
AUTHOR
L. Dimitrocenko
Characterization of Crystalline Structure and Morphology of Ga<sub>2</sub>O<sub>3</sub> Thin Film Grown by MOCVD Technique
Growth of gallium oxide thin film was realized with MOCVD on (0001) sapphire substrate. Structural and compositional properties of thin film were studied employing trimethylgallium and water as precursors, carrier gases were H2 and N2. Obtained film is polycrystalline and predominantly consisted of (201) oriented β-Ga2O3. Sample exhibited blue luminescence which is attributed to oxygen vacancies. H2 gas proved to have beneficial effect on film quality and overall growth process.
Luminescence of Ce‐doped borate‐oxyfluoride glass ceramics
In the present work we studied the possibility to obtain oxyfluoride glass ceramics based on a lithium and potassium borate glasses with addition of fluorides. Lithium-borate glasses without lanthanum fluoride are transparent up to 275 nm. In samples with LaF3 doped with Ce-activator, an additional absorption at about 300 nm and intense photoluminescence could be observed. Ce-doped potassium-borate glass with addition of fluorides LaF3, LiF and GdF3 was milky and not transparent, an intense photoluminescence has been observed, X-ray diffraction measurements showed a presence of well-pronounced crystalline phases of LiF as well as of GdBO3. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Growth temperature influence on the GaN nanowires grown by MOVPE technique
GaN nanowires (NWs) were successfully grown by Vapor-Liquid-Solid (VLS) growth mechanism on GaN template using metal-organic vapor phase epitaxy (MOVPE) with diameters ranging from 20 to 200 nm and length up to few microns. The characterization by scanning electron microscopy (SEM) reveals an optimum growth temperature at 790°C and X-ray diffraction (XRD) investigations indicates oriented crystallinity of grown NWs.
Dynamics of exciton creation and decay processes in composition – disordered InGaN thin films
In the GaN-based ternary alloys, InGaN crystals have been recognized as key materials for e-h plasmas-exciton dynamics, because of large exciton binding energies (24.8 meV in GaN). We report investigations of creating and recombination dynamics of excitons in commercially important InxGa1-xN composition range from x = 0.1 to 0.18 in which nanoscale indium composition fluctuation occurs and formation of indium rich clusters acting as quantum dots (QD) can be expected. Three MOCVD grown samples having x = 0.1; 0.14 and 0.18 have been investigated using 3D picosecond transient PL spectroscopy. It has been found that the band to band photo excitation at 15 K in whole composition range results i…
<title>Formation of deep acceptor centers in AlGaN alloys</title>
AlGaN alloy thin film materials are of high interest for light emitting diodes (LED of the ultraviolet (UV) spectral region. Origin of the deep intrinsic and impurity Si states in the AlxGa1-xN (0 < x < 0.35) epilayer structures grown by metalorganic chemical vapor deposition (MOCVD) technique have been considered. Effects of the lattice mismatch and Si-doping in the heterostructures of epilayers with different alloy composition are investigated using time resolved photoluminescence (PL) of donor – deep acceptor (DA) pairs. It is shown that the undoped AlGaN alloys, grown on a GaN buffer layer, due to the lattice mismatch contain the increased concentration of cation vacancy (Vcation) defec…
Ex situ investigations of MOCVD-grown gallium nitride nanowires using reflection high energy electron diffraction
Vertically oriented nanowires (NWs) of single-crystalline wurtzite GaN have been fabricated on sapphire substrates, via metal organic chemical vapor deposition (MOCVD). We present ex situ investigations on orientation and structure of grown GaN nanowires on GaN(0001) surface using reflection high energy electron diffraction (RHEED). Both ordered and randomly oriented GaN crystalline structures have been detected.