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Vilnius, Lithuania

Maertens A.,CNRS Laboratory of Optical Materials, Photonics, and Systems | Margueron S.,CNRS Laboratory of Optical Materials, Photonics, and Systems | Genty F.,CNRS Laboratory of Optical Materials, Photonics, and Systems | Kuprenaite S.,Vilnius UniversityVilnius | And 2 more authors.
Journal of Nanoelectronics and Optoelectronics | Year: 2015

In this paper, the effects of zinc proportion in structural, electrical, and optical properties of In2O3 thin films were investigated. 100 nm-thick crystallize indium-zinc-oxide (IZO) thin films were grown by spray pyrolysis method on C-plan sapphire, (001)-silicon, (001)-GaN template and YSZ substrates. The electrical conductivity measurements show a strong influence of the substrates. The best composition for 3 μm Vertical Cavity Surface Emitting Laser (VCSEL) top contact is found at 30% at. Zn with a maximum IR transparency of 80%. The possibility to synthetize a p-type thin films was also demonstrated. Copyright © 2015 American Scientific Publishers. Source


Pitsevich G.A.,Belarusian State University of Informatics and Radioelectronics | Malevich A.E.,Belarusian State University of Informatics and Radioelectronics | Kozlovskaya E.N.,Belarusian State University of Informatics and Radioelectronics | Doroshenko I.Y.,Taras Shevchenko National University | And 4 more authors.
Vibrational Spectroscopy | Year: 2015

Abstract The structure and IR absorption spectrum of the formic acid dimer (FAD) were calculated using the B3LYP DFT functional and cc-pVTZ basis set. Matrices of force and anharmonic constants were calculated in order to find the fundamental frequencies more accurately. The 1D and 2D potential energy surfaces (PES) were built using symmetry coordinates and stretching coordinates of CH and OH bonds. For OH stretching coordinates, the 2D PES were built with and without optimization of the remaining geometric parameters. It was shown that in the second case besides the global minimum, an additional local minimum on the unrelaxed PES is formed with the energy more than 4000 cm-1 higher than the energy of the ground state. A numerical solution of Schrödinger equations gives the values of OH and CH stretching vibrations. Comparison of the obtained theoretical results with the experimental data presented in the literature allowed us to make new assignments for IR and Raman spectral bands related to hydroxyl groups stretching vibrations in FAD. © 2015 Elsevier B.V. Source


Scajev P.,Vilnius UniversityVilnius | Jurkevicius J.,Vilnius UniversityVilnius | Mickevicius J.,Vilnius UniversityVilnius | Jarasiunas K.,Vilnius UniversityVilnius | Kato H.,Japan National Institute of Advanced Industrial Science and Technology
Diamond and Related Materials | Year: 2015

We investigated carrier dynamics and photoluminescence in undoped and n-type phosphorus-doped diamond epilayers under interband picosecond-pulse photoexcitation at 213 nm. Carrier/exciton lifetime and diffusion coefficient D were determined in 4 × 1017 to 4 × 1019 cm- 3 carrier density range. The low D = 7 ÷ 11 cm2/s value in the undoped epilayer was ascribed to exciton formation and contribution of many-body effects. At low excitations, photoluminescence spectra in the undoped layer exhibited exciton emission, while at the higher ones (above 2 × 1018 cm- 3) free carrier emission became dominant. The calculated radiative lifetime of excitons (860 ns) was found much higher than the experimentally measured nonradiative lifetime of 11 ns, governed by excess carrier diffusive flow to the surface, with S = (3 ± 2) × 105 cm/s surface recombination velocity. In the n-type layer, donor-related emission dominated and the phosphorus-related defect complexes diminished the carrier lifetime to 30-50 ps. Optically recharged phosphorus states resulted in millisecond long decay tails of trapped carriers. © 2015 Elsevier B.V. Source

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