Enhancing SiGeSn nanocrystals SWIR photosensing by high passivation in nanocrystalline HfO matrix.

SiGeSn nanocrystals (NCs) in oxides are of considerable interest for photo-effect applications due to the fine-tuning of the optical bandgap by quantum confinement in NCs. We present a detailed study regarding the silicon germanium tin (SiGeSn) NCs embedded in a nanocrystalline hafnium oxide (HfO) matrix fabricated by using magnetron co-sputtering deposition at room temperature and rapid thermal annealing (RTA). The NCs were formed at temperatures in the range of 500-800 °C.

Titania nanoparticles for photocatalytic degradation of ethanol under simulated solar light.

TiO nanoparticles were synthesized by laser pyrolysis from TiCl vapor in air in the presence of ethylene as sensitizer at different working pressures (250-850 mbar) with and without further calcination at 450 °C. The obtained powders were analyzed by energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, X-ray diffractometry, and transmission electron microscopy. Also, specific surface area and photoluminescence with optical absorbance were evaluated.

Ferroelectric Orthorhombic ZrO Thin Films Achieved Through Nanosecond Laser Annealing.

A new approach for the stabilization of the ferroelectric orthorhombic ZrO films is demonstrated through nanosecond laser annealing (NLA) of as-deposited Si/SiO /W(14 nm)/ZrO (8 nm)/W(22 nm), grown by ion beam sputtering at low temperatures. The NLA process optimization is guided by COMSOL multiphysics simulations. The films annealed under the optimized conditions reveal the presence of the orthorhombic phase, as confirmed by X-ray diffraction, electron backscatter diffraction, and transmission electron microscopy.

Structural, Optical, and Sensing Properties of Nb-Doped ITO Thin Films Deposited by the Sol-Gel Method.

The aim of the present study was the development of Nb-doped ITO thin films for carbon monoxide (CO) sensing applications. The detection of CO is imperious because of its high toxicity, with long-term exposure having a negative impact on human health. Using a feasible sol-gel method, the doped ITO thin films were prepared at room temperature and deposited onto various substrates (Si, SiO/glass, and glass).

Multifunctional Zn-Doped ITO Sol-Gel Films Deposited on Different Substrates: Application as CO-Sensing Material.

Undoped and Zn-doped ITO (ITO:Zn) multifunctional thin films were successfully synthesized using the sol-gel and dipping method on three different types of substrates (glass, SiO/glass, and Si). The effect of Zn doping on the optoelectronic, microstructural, and gas-sensing properties of the films was investigated using X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), spectroscopic ellipsometry (SE), Raman spectroscopy, Hall effect measurements (HE), and gas testing. The results showed that the optical constants, the transmission, and the carrier numbers were correlated with the substrate type and with the microstructure and the thickness of the films.

Graphene/Ferroelectric (Ge-Doped HfO) Adaptable Transistors Acting as Reconfigurable Logic Gates.

We present an array of 225 field-effect transistors (FETs), where each of them has a graphene monolayer channel grown on a 3-layer deposited stack of 22 nm control HfO/5 nm Ge-HfO intermediate layer/8 nm tunnel HfO/-Si substrate. The intermediate layer is ferroelectric and acts as a floating gate. All transistors have two top gates, while the -Si substrate is acting as a back gate.

Nanocrystallized Ge-Rich SiGe-HfO Highly Photosensitive in Short-Wave Infrared.

Group IV nanocrystals (NCs), in particular from the Si-Ge system, are of high interest for Si photonics applications. Ge-rich SiGe NCs embedded in nanocrystallized HfO were obtained by magnetron sputtering deposition followed by rapid thermal annealing at 600 °C for nanostructuring. The complex characterization of morphology and crystalline structure by X-ray diffraction, μ-Raman spectroscopy, and cross-section transmission electron microscopy evidenced the formation of Ge-rich SiGe NCs (3-7 nm diameter) in a matrix of nanocrystallized HfO.

Thickness-Dependent Photoelectrochemical Water Splitting Properties of Self-Assembled Nanostructured LaFeO Perovskite Thin Films.

Tuning the intrinsic structural and stoichiometric properties by different means is used for increasing the green energy production efficiency of complex oxide materials. Here, we report on the formation of self-assembled nanodomains and their effects on the photoelectrochemical (PEC) properties of LaFeO (LFO) epitaxial thin films as a function of layer's thickness. The variation with the film's thickness of the structural parameters such as in-plane and out-of-plane crystalline coherence length and the coexistence of different epitaxial orientation-<100>SrTiO//<001> LFO, <100>SrTiO//<110> LFO and [110] LFO//[10] STO, as well as the appearance of self-assembled nanodomains for film's thicknesses higher than 14 nm, is presented.

The Influence of the Structural and Morphological Properties of WO Thin Films Obtained by PLD on the Photoelectrochemical Water-Splitting Reaction Efficiency.

Due to its physical and chemical properties, the n-type tungsten oxide (WO) semiconductor is a suitable photoanode for water decomposition reaction. The responses of the photoelectrochemical PEC water-splitting properties as an effect of structural and optical changes of WO thin films, as well as the nature of electrolyte solutions, were studied in this work. The WO thins films have been obtained by pulsed laser deposition (PLD) on silicon (Si(001)) covered with platinum substrates using three different laser wavelengths.

GeSn/SiO Multilayers by Magnetron Sputtering Deposition for Short-Wave Infrared Photonics.

The development of short-wave infrared (SWIR) photonics based on GeSn alloys is of high technological interest for many application fields, such as the Internet of things or pollution monitoring. The manufacture of crystalline GeSn is a major challenge, mainly because of the low miscibility of Ge and Sn. The use of embedded GeSn nanocrystals (NCs) by magnetron sputtering is a cost-effective and efficient method to relax the growth conditions.

Epitaxial GeSn Obtained by High Power Impulse Magnetron Sputtering and the Heterojunction with Embedded GeSn Nanocrystals for Shortwave Infrared Detection.

GeSn alloys have the potential of extending the Si photonics functionality in shortwave infrared (SWIR) light emission and detection. Epitaxial GeSn layers were deposited on a relaxed Ge buffer on Si(100) wafer by using high power impulse magnetron sputtering (HiPI-MS). Detailed X-ray reciprocal space mapping and HRTEM investigations indicate higher crystalline quality of GeSn epitaxial layers deposited by Ge HiPI-MS compared to commonly used radio frequency magnetron sputtering (RF-MS).

SiGe nanocrystals in SiO with high photosensitivity from visible to short-wave infrared.

Films of SiGe nanocrystals (NCs) in oxide have the advantage of tuning the energy band gap by adjusting SiGe NCs composition and size. In this study, SiGe-SiO amorphous films were deposited by magnetron sputtering on Si substrate followed by rapid thermal annealing at 700, 800 and 1000 °C. We investigated films with Si:Ge:SiO compositions of 25:25:50 vol.

Fabrication and characterization of Si Ge nanocrystals in as-grown and annealed structures: a comparative study.

Multilayer structures comprising of SiO/SiGe/SiO and containing SiGe nanoparticles were obtained by depositing SiO layers using reactive direct current magnetron sputtering (dcMS), whereas, Si and Ge were co-sputtered using dcMS and high-power impulse magnetron sputtering (HiPIMS). The as-grown structures subsequently underwent rapid thermal annealing (550-900 °C for 1 min) in N ambient atmosphere. The structures were investigated using X-ray diffraction, high-resolution transmission electron microscopy together with spectral photocurrent measurements, to explore structural changes and corresponding properties.

Tryptophan / Dextran70 Based - Fluorescent Silver Nanoparticles: Synthesis and Physicochemical Properties.

Nano-size and shape of fluorescent silver nanostructures are important for a wide range of bio-applications, especially as drug delivery systems, imaging and sensing. The aim of the work is to develop a fluorescent silver nano-structured system, synthesized by chemical reduction of aqueous AgNO solution by Tryptophan using Dextran 70 as stabilizing agent (SNPs). The formed fluorescent nano-system was analyzed by UV-Vis absorption, DLS, SEM, TEM, AFM, steady-state and time resolved fluorescence spectroscopy.

Ge nanoparticles in SiO for near infrared photodetectors with high performance.

In this work we prepared films of amorphous germanium nanoparticles embedded in SiO deposited by magnetron sputtering on Si and quartz heated substrates at 300, 400 and 500 °C. Structure, morphology, optical, electrical and photoconduction properties of all films were investigated. The Ge concentration in the depth of the films is strongly dependent on the deposition temperature.

Sensors based on mesoporous SnO-CuWO with high selective sensitivity to HS at low operating temperature.

Development of new sensitive materials by different synthesis routes in order to emphasize the sensing properties for hazardous HS detection is one of a nowadays challenge in the field of gas sensors. In this study we obtained mesoporous SnO-CuWO with selective sensitivity to HS by an inexpensive synthesis route with low environmental pollution level, using tripropylamine (TPA) as template and polyvinylpyrrolidone (PVP) as dispersant/stabilizer. In order to bring insights about the intrinsic properties, the powders were characterized by means of a variety of complementary techniques such as: X-Ray Diffraction, XRD; Transmission Electron Microscopy, TEM; High Resolution TEM, HRTEM; Raman Spectroscopy, RS; Porosity Analysis by N adsorption/desorption, BET; Scanning Electron Microscopy, SEM and X-ray Photoelectron Spectroscopy, XPS.

Multiscale investigation of USPIO nanoparticles in atherosclerotic plaques and their catabolism and storage in vivo.

The storage and catabolism of Ultrasmall SuperParamagnetic Iron Oxide (USPIO) nanoparticles were analyzed through a multiscale approach combining Two Photon Laser Scanning Microscopy (TPLSM) and High-Resolution Transmission Electron Microscopy (HRTEM) at different times after intravenous injection in an atherosclerotic ApoE(-/-) mouse model. The atherosclerotic plaque features and the USPIO heterogeneous biodistribution were revealed down from organ's scale to subcellular level. The biotransformation of the nanoparticle iron oxide (maghemite) core into ferritin, the non-toxic form of iron storage, was demonstrated for the first time ex vivo in atherosclerotic plaques as well as in spleen, the iron storage organ.

Physicochemical Characterization and In Vitro Cytotoxic Effect of 3-Hydroxyflavone in a Silver Nanoparticles Complex.

The aim of this work was to characterize the physico-chemical properties of 3-hydroxyflavone (3-HF) in a silver nanoparticles complex (SNPs) using UV-vis and Fluorescence spectroscopy, Atomic Force Microscopy (AFM) and Transmission Electron Microscopy (TEM) analysis. One also evaluated its effect on the cell viability and morphology of L929 mouse fibroblast cells in vitro. The contribution of the carrier protein, Bovine Serum Albumin (BSA) to 3-HF properties has also been investigated.

On the photocatalytic reduction of MTT tetrazolium salt on the surface of TiO2 nanoparticles: Formazan production kinetics and mechanism.

Hypothesis: The MTT [3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium-bromide] cell cytotoxicity indicator is photocatalytically reduced on the surface of TiO2 nanoparticles in phosphate-buffered-saline (PBS) environment. We hypothesize that specific phosphate adsorption may be used to modulate the efficiency of the TiO2-MTT reaction through colloidal and semiconductor-liquid interface processes.

Experiments: The TiO2-MTT reaction kinetics was studied in PBS, with respect to photocatalyst and MTT concentrations and irradiation wavelength.

Nanostructuring of GeTiO amorphous films by pulsed laser irradiation.

Laser pulse processing of surfaces and thin films is a useful tool for amorphous thin films crystallization, surface nanostructuring, phase transformation and modification of physical properties of thin films. Here we show the effects of nanostructuring produced at the surface and under the surface of amorphous GeTiO films through laser pulses using fluences of 10-30 mJ/cm(2). The GeTiO films were obtained by RF magnetron sputtering with 50:50 initial atomic ratio of Ge:TiO2.

Si/SiO2 quantum dots cause cytotoxicity in lung cells through redox homeostasis imbalance.

Si/SiO2 quantum dots (QDs) are novel particles with unique physicochemical properties that promote them as potential candidates for biomedical applications. Although their interaction with human cells has been poorly investigated, oxidative stress appears to be the main factor involved in the cytotoxicity of these nanoparticles. In this study, we show for the first time the influence of Si/SiO2 QDs on cellular redox homeostasis and glutathione distribution in human lung fibroblasts.

Electrical behavior of multi-walled carbon nanotube network embedded in amorphous silicon nitride.

The electrical behavior of multi-walled carbon nanotube network embedded in amorphous silicon nitride is studied by measuring the voltage and temperature dependences of the current. The microstructure of the network is investigated by cross-sectional transmission electron microscopy. The multi-walled carbon nanotube network has an uniform spatial extension in the silicon nitride matrix.

Fast and simple specimen preparation for TEM studies of oxide films deposited on silicon wafers.

We present a fast and simple method to prepare specimens for transmission electron microscopy studies of oxide thin films deposited on silicon substrates. The method consists of scratching the film surface using a pointed diamond tip, in a special manner. Small and thin fragments are then detached from the film and its substrate.