Ion Tiginyanu

Ion Tiginyanu
Academy of Sciences and Technical University of Moldova

Academician, Professor, Dr.

About

525
Publications
35,970
Reads
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7,842
Citations
Additional affiliations
November 2004 - present
Academy of Sciences of Moldova and Technical University of Moldova
Position
  • First Vice-President and University Professor
September 1988 - present
Technical University of Moldova
Position
  • Professor, Director of the National Center for Materials Study and Testing

Publications

Publications (525)
Article
Full-text available
The preparation of GaAs nanowire templates with the cost-effective electrochemical etching of (001) and (111)B GaAs substrates in a 1 M HNO3 electrolyte is reported. The electrochemical etching resulted in the obtaining of GaAs nanowires with both perpendicular and parallel orientations with respect to the wafer surface. Core–shell GaAs-Fe nanowire...
Chapter
In this paper we present a systematic study of bulk GaAs wafers and gold-decorated GaAs surfaces exhibiting hydrophilic and hydrophobic behaviors. The wetting properties can be switched to superhydrophilicity and superhydrophilicity by simple electrochemical etching providing engineered porous morphologies. The results open interesting technologica...
Chapter
Full-text available
In this paper Zn1-xMgxO thin films with composition range x = 0.00–0.80 have been obtained by aerosol spray deposition method on p-Si substrates by using zinc acetate and magnesium acetate as precursors. The produced thin films were characterized by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, X-ray diffraction (XRD),...
Article
Full-text available
A series of Zn 1−x Mg x O thin films with the composition range x = 0.00-0.60 has been prepared by aerosol spray pyrolysis deposition on Si or quartz substrates. The morphology, composition, crystals structure, and optical properties of the prepared films were studied by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), X-...
Article
Full-text available
This paper reports a joint experimental and theoretical study of the electronic band structure of two ordered-vacancy compounds with defect-chalcopyrite structure: CdGa2S4 and HgGa2S4. High-pressure optical-absorption experiments (up to around 17 GPa) combined with first-principles electronic band-structure calculations provide compelling evidence...
Conference Paper
Full-text available
The structure of the photodetector with Schottky Ag-Zn0.65Mg0.35O barrier and with a gradient of the band gap in the detector active region is shown in (Fig.1). The energy diagram of the structure with two oxide compound layers, forming a gradient of the band gap (Fig. 2). The discontinuity in the valence band (VB) and the conduction band (CB) betw...
Article
Full-text available
Thin ZnSnO films with different thickness deposited on Si substrates by aerosol spray pyrolysis were investigated by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD), atomic force microscopy (AFM) and light microscopy (LM) using depth-sensitive nanoindentation with Berkovich indenter. The values of...
Article
Full-text available
Thin ZnSnO films with different thickness deposited on Si substrates by aerosol spray pyrolysis were investigated by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD), atomic force microscopy (AFM) and light microscopy (LM) using depth-sensitive nanoindentation with Berkovich indenter. The values of...
Article
Rezumat: În lucrare este descrisă aplicarea proceselor electrochimice în nanotehnologii pentru obținerea diferitelor obiecte la scală nanometrică cu morfologie predefinită și poziționare controlată. Este explicat mecanismul „electrodepunerii prin salturi” care permite depunerea unui monostrat de puncte de Au. Metodele electrochimice abordate în ace...
Conference Paper
Full-text available
ZnMgO thin films were prepared on Si substrates by aerosol deposition method using zinc acetate and magnesium acetate as precursors. The obtained films were investigated by scanning electron microscopy (SEM), energy dispersive x-ray (EDX) and X-Ray Diffraction (XRD). SEM and EDX analysis showed that the produced thin films are homogeneous from the...
Article
Full-text available
In this work, the β-Ga2O3 nanostructures were obtained by thermal annealing in air of β-Ga2S3 single crystals at relatively high temperatures of 970 K, 1070 K and 1170 K for 6 h. The structural, morphological, chemical and optical properties of β-Ga2O3–β-Ga2S3 layered composites grown at different temperatures were investigated by means of X-ray di...
Chapter
Full-text available
Zn1−xMgxO thin films were prepared by aerosol deposition and spin-coating method, using zinc acetate and magnesium acetate as precursors. The obtained films were investigated by scanning electron microscopy (SEM), electrical and photoelectrical characterization. SEM and energy dispersive x-ray (EDX) analysis has shown that the produced thin films a...
Preprint
Full-text available
NiO presents interest for a wide range of optoelectronic application as a p-type transparent conducting films due to the wide band gap (3.6-4,0 eV). Furthermore, its excellent durability and electrochemical stability is important for optical applications. NiO thin films have been fabricated by various physical and chemical deposition techniques, su...
Poster
Full-text available
Here we report on Au catalyzed growth of ZnS NWs via Hydride Vapor Phase Epitaxial (HVPE) process and their crystallographic analysis and defect evaluation by TEM techniques. ZnS NWs of two different morphologies and crystal structures obtained in the same process. The type of crystal structure and the nature of defects are revealed by combined SAE...
Conference Paper
Full-text available
1. Introduction Semiconductor nanowires (NWs) are widely required for assembly of electronic and photonic devices. In particular, direct wide band gap ZnS NWs can serve as building blocks for sensor, LED and laser applications, quantum computing or UV-energy conversion. For their integration into devices low or controllable level of defects represe...
Article
Gallium oxide (β-Ga2O3) nanowires were synthesized by heat treatment of single crystal β-GaS plates in air. Crystal structure and composition of synthesized materials were studied by X-ray diffraction, energy dispersive X-ray spectroscopy and Raman spectroscopy. Thermal treatment of β-GaS plates at 1023 K leads to the formation of a Ga2O3 (native o...
Article
– We report on the application of specially-designed masks for the purpose of electrochemical etching of InP single crystals which enables one to change in a controlled fashion the direction of propagation of pores, including those propagating in directions parallel to the top surface of substrates. The fabricated templates have been used to electr...
Article
Raman scattering measurements have been performed in cadmium digallium sulphide (CdGa2S4) with defect chalcopyrite structure up to 25 GPa in order to study its pressure-induced phase transitions. These measurements have been complemented and compared with lattice-dynamics ab initio calculations including the TO-LO splitting at high pressures in ord...
Article
Full-text available
In this paper, we report on results of a systematic study of porous morphologies obtained using anodization of HVPE-grown crystalline GaN wafers in HNO3, HCl, and NaCl solutions. The anodization-induced nanostructuring is found to proceed in different ways on N- and Ga-faces of polar GaN substrates. Complex pyramidal structures are disclosed and sh...
Article
“Retroreflected light with strong linear polarization coinciding with that of the incident beams is detected from strongly absorbing nanoporous III–V semiconductors. Because of high polarization of retroreflected waves we assume that coherent backscattering is the underlying physical mechanism of this phenomenon”.
Article
Nature utilizes hydrophilic-hydrophobic biomolecular entities to perform self-organized structural and functional tasks, including the formation of cellular compartments and motion, separation of chemicals or self-healing properties in a highly energy efficient manner. So far, no inorganic artificial micro/nanostructure units are known that self-or...
Article
Novel gas sensors have been realized by decorating clusters of tubular Aerographite with CdTe using magnetron sputtering techniques. Subsequently, individual microtubes were separated and electrically contacted on a SiO2/Si substrate with pre-patterned electrodes. Cathodoluminescence, electron microscopy and electrical characterization prove the su...
Article
We demonstrate experimentally that single crystalline GaN nanomembranes arranged in simple networks exhibit learning mechanisms such as habituation and dishabituation followed by storage of the response to a certain electrical stimulus. These artificial learning mechanisms are analogous to non-associative learning processes which are identical in s...
Article
Full-text available
In the present work, we report on development of three-dimensional flexible architectures consisting of an extremely porous three-dimensional Aerographite (AG) backbone decorated by InP micro/nanocrystallites grown by a single step hydride vapor phase epitaxy process. The systematic investigation of the hybrid materials by scanning electron microsc...
Article
Full-text available
We report on anomalous light retroreflection from strongly absorbing nanoporous semiconductor materials, GaAs and InP, with strongly polarized retroreflected light with linear polarization coinciding with that of incident beams. The high polarization of retroreflected waves suggests coherent backscattering as the underlying physical mechanism. This...
Article
Full-text available
Tin oxide nanowires (SnO2 NWs) exhibit large potential for applications in sensor and detector technology. Using a flame transport synthesis method, high-quality single crystalline SnO2 nanowires (NWs) with Zn2SnO4 dots functionalized surface were synthesized on a large scale. The individual SnO2:Zn2SnO4 nanowire based ultraviolet photodetector and...
Article
In this paper, we report on functionalization of graphene aerogel with a CdS thin film deposited by magnetron sputtering and on the development of flexible pressure sensors based on ultra-lightweight CdS-aerogel nanocomposite. Analysis by scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray analysis disclose th...
Article
We report the fabrication and characterization of SnO2/CdTe and SnO2/GaAs core/shell microstructures. CdTe or GaAs shell layers were deposited by radio-frequency (RF) magnetron sputtering on core SnO2 microwires synthesized by a flame-based thermal oxidation method. The produced structures were characterized by scanning electron microscopy (SEM), h...
Article
Full-text available
In this work, a simple method of ZnAl2O4-functionalization of ZnO microstructures is presented. The different characterization methods (structural, chemical and micro-Raman) demonstrated the presence of only ZnO and ZnAl2O4 crystalline phases. ZnAl2O4 nano-crystallites grow on the surfaces of ZnO 3D microstructures having diameters of 50-100 nm and...
Article
The structural morphology of metal oxide nano- and microstructures plays a crucial role in the performances of sensors and especially of nanosensors. Here, a simple approach on the synthesis of three-dimensional (3D) highly porous ZnO nano- and microstructure networks with four different arm morphologies in the same process is reported. Systematic...
Article
We demonstrate experimentally that a sample of a SnS2 layered semiconductor compound with the area of 1 cm² and the thickness of 100 μm, contacted laterally by silver electrodes with the area of 1 mm², acts naturally as a memristor device when illuminated by a sun simulator. Although the conductance of the device changes with the number of pulses o...
Article
Full-text available
In this paper, we report on the interaction of multifunctional nanoparticles with living endothelial cells. The nanoparticles were synthesized using direct growth of gallium nitride on zinc oxide nanoparticles alloyed with iron oxide followed by core decomposition in hydrogen flow at high temperature. Using transmission electron microscopy, we demo...
Conference Paper
We report on the application of special design of masks for the purpose of electrochemical etching of InP single crystals which enables one to change in a controlled fashion the direction of propagation of pores, including those propagating in directions parallel to the top surface of substrates. The fabricated templates have been used to electroch...
Article
In this work, the UV and gas sensing properties of single Fe-doped and Fe2O3-functionalized ZnO micro- and nanowires are reported. The influence of microwire diameter and concentration of Fe2O3 nanoparticles on the sensing properties of the fabricated devices was investigated. Results clearly reveal that sensors with a higher response can be obtain...
Article
Full-text available
We report the results of calculations of several optical parameters of ZnSxSe1-x thin films, based on measured transmission spectra, by using the Swanepoel’s method, the Wemple-DiDomenico single-oscillator model, and the Sellmeier single-oscillator model. The following optical constants have been determined: the refractive index n(), the extinctio...
Article
This article reviews the main physical properties of atomically thin semiconductors and the electronic devices based on them. We start with graphene, describing its physical properties and growth methods, followed by a discussion of its electronic device applications. Then, transition metal dichalcogenides (TMDs) are analyzed as a prototype of atom...
Article
Full-text available
In this work, the exceptionally improved sensing capability of highly porous three-dimensional (3-D) hybrid ceramic networks toward reducing gases is demonstrated for the first time. The 3-D hybrid ceramic networks are based on doped metal oxides (MexOy and ZnxMe1-xOy, Me= Fe, Cu, Al) and alloyed zinc oxide tetrapods (ZnO-T) forming numerous juncti...
Article
A novel method to improve and tune gas sensing properties of the ZnO tetrapod networks by alloying with MexOy and ZnxMe1-xOy is reported. Due to the catalytic effect of the alloyed materials (Me=Fe, Cu or Al), a change in selectivity of the hybrid networks is demonstrated. Synthesized highly porous hybrid networks can serve as a novel material for...
Article
Electroplating is shown to represent a simple and effective tool for assessing the conductivity of InP nanostructures fabricated by electrochemical etching of InP wafers. A mixture of nanowalls, nanowires and nanobelts was fabricated by anodic etching of crystalline bulk n-InP with free electron concentration of 1.3×10¹⁸ cm⁻³ under applied voltage...
Article
Methylammonium lead-halide perovskites are very promising for applications as solar light-harvesting materials. This paper presents a study on the methylammonium iodide and iodide-chloride perovskite films prepared by spin coating from a liquid precursor. The powder diffraction spectroscopy has detected 10 lattice plane reflections common to a pero...
Article
Full-text available
Thin ZnSxSe1-x films on glass substrates have been obtained by thermal evaporation. Electrodes from In or other materials have been deposited on thin films, and the temperature dependence of electrical conductivity was investigated during a series of successive cycles of heating and cooling performed at a rate of 6 K/min in a temperature interval f...
Article
In this paper the mechanisms of previously experimentally observed anomalous retroreflection in a strongly absorbing nanostructured medium are explained by using 'dark' and 'bright' modes. The observed regularities are analyzed for both s-polarized and p-polarized incident radiation with respect to the contribution from 'dark' and 'bright' modes an...
Article
In this paper we report on a comparative study of electrochemical processes for the preparation of multilayer porous structures in hydride vapor phase epitaxy (HVPE) and metal organic chemical vapor phase deposition (MOCVD) grown GaN. It was found that in HVPE-grown GaN, multilayer porous structures are obtained due to self-organization processes l...
Article
Full-text available
We developed technological procedures for preparation of filiform nanostructures (FNSs) on the basis of stretching microwires with magnetic material cores. It is shown that disruptions of the microwire core occur for these materials during technological process of stretching due to relatively high melting temperature of magnetic alloys. As a result...
Article
In this paper, we report on a pressure sensor based on graphene aerogel functionalized with SnO2 or GaN thin films deposited by magnetron sputtering. Decoration by nanocrystalline SnO2 or GaN was found to enhance the piezoresistive response of the bare aerogel. The responsivity and pressure sensing range (from 1-5 atm) of the sensor are shown to be...
Article
Full-text available
On page 5497, M. Guix and co-workers demonstrate a novel light-driven microengine consisting of arrays of self-arranged titanium dioxide nanotubes with a conical inner diameter. Under exposure to UV irradiation, the microengine shows directed motion in solution, both in the presence and absence of hydrogen peroxide, and exhibits cargo capabilities,...
Article
Full-text available
Nanotechnology is a rapidly growing and promising field of interest in medicine; however, nanoparticle-cell interactions are not yet fully understood. The goal of this work was to examine the interaction between endothelial cells and gallium nitride (GaN) semiconductor nanoparticles. Cellular viability, adhesion, proliferation, and uptake of nanopa...
Data
Details regarding nanoparticle characterization, chemical analysis measurements and schematics of the surface functionalization process with nanoparticles.
Article
Full-text available
In present work, the nano- and microscale tetrapods from zinc oxide were integrated on the surface of Aerographite material (as backbone) in carbon-metal oxide hybrid hierarchical network via a simple and single step magnetron sputtering process. The fabricated hybrid networks are characterized for morphology, microstructural and optical properties...
Article
An electrochemical approach for manufacturing light-driven nanostructured titanium dioxide (TiO2) microengines with controlled spatial architecture for improved performance is reported. The microengines based on microscale arrays of TiO2 nanotubes with variable (50–120 nm) inner diameter show a quasi-ordered arrangement of nanotubes, being the smal...
Article
We present a review of the investigations realized in the last decades of the phenomenon of the Bose-Einstein condensation (BEC) in the system of two-dimensional cavity polaritons in semiconductor nanostructures. The conditions at which the excitons interacting with cavity photons form new type of quasiparticles named as polaritons are described....
Article
In this paper, we show that ultrathin GaN membranes having a thickness of 15 nm and planar dimensions of 12x184 microns act as memristive devices. This fact is due to the migration of the negatively charged deep traps, which form in the volume of the membrane during the fabrication process, towards the unoccupied surface states of the suspended mem...