Optical and structural characterization of Ge clusters embedded in ZrO2

The change of optical and structural properties of Ge nanoclusters in ZrO2 matrix have been investigated by spectroscopic ellipsometry versus annealing temperatures. Radio-frequency top-down magnetron sputtering approach was used to produce the samples of different types, i.e. single-layers of pure Ge, pure ZrO2 and Ge-rich-ZrO2 as well as multi-layers stacked of 40 periods of 5-nm-Ge-rich-ZrO2 layers alternated by 5-nm-ZrO2 ones. Germanium nanoclusters in ZrO2 host were formed by rapid-thermal annealing at 600-800 ∘C during 30 s in nitrogen atmosphere. Reference optical properties for pure ZrO2 and pure Ge have been extracted using single-layer samples. As-deposited multi-layer structures can be perfectly modeled using the effective medium theory. However, annealed multi-layers demonstrated a significant diffusion of elements that was confirmed by medium energy ion scattering measurements. This fact prevents fitting of such annealed structure either by homogeneous or by periodic multi-layer model

Privacy, Trust and Interaction in the Internet of Things

Abstract. This workshop addresses topics of increasing importance in the emerging area of the Internet of Things (IoT): privacy, trust and related interaction concepts. The aim of the workshop is to bring together experts from different areas to cover the complexity of the questions involved and to provide a forum for developing new ideas on how to address the major challenges in the field considering both a scientific and an industrial viewpoint. The workshop targets to identify pressing questions and to develop a research agenda for trusted and privacy-respecting computing in the IoT. Special attention within the workshop is given on whether and how experiences with privacy and trust from related areas can be applied to the IoT, where existing conceptualizations need to be extended or modified and where radically new concepts are required. The Internet of Things (IoT) is an umbrella term covering a number of different base technologies aimed at linking physical objects and their virtual representation with the goal to utilize this link for improved service and interaction concepts [3]. The IoT approach combines concepts and paradigms informed by Ambient Intelligence, Ubiquitou

Оптичні властивості плівок оксиду ванадію

Як типовий корельований електронний матеріал, діоксид ванадію VO2 демонструє перехід метал-діелектрик при відносно низькій температурі. При нагріванні відбувається перехід від діелектричної моноклінної фази до металевої тетрагональної фази (структура рутилу) з перегрупуванням іонів ванадію вздовж осі моноклінної гратки. Зміна фази відповідає колосальному падінню питомого опору більш ніж на чотири порядки, а також іншим змінам властивостей, які можуть бути оборотними через природний процес охолодження. Таким чином, VO2 привернув велику увагу при його застосуванні у високочутливих розумних пристроях, які можуть різко реагувати на різноманітні зовнішні впливи. В останні роки швидкий прогрес у виробництві та модуляції властивостей VO2 значно полегшив його застосування в багатьох аспектах, таких як термічне зондування, термохроміка, електроніка та механіка з множинним відгуком. Методом модуляційної поляриметрії досліджено оптичні властивості тонких плівок діоксиду ванадію. Для осадження тонкої плівки VO2 використовувався двоетапний метод. Плівки VO2 вирощували на підкладках з кварцового скла шляхом магнетронного розпилення мішені VO2 з подальшим термічним відпалом. Плівки мали різні модифікації складу, структури, морфології та оптичних властивостей, зумовлені технологією виготовлення. У роботі було виміряно кутові залежності коефіцієнтів відбивання електромагнітного випромінювання s- і pполяризацій і їх різницю для різних довжин хвиль. Поляризаційні характеристики були змодельовані за допомогою матричного перетворення формул Френеля. Значення показників заломлення та поглинання плівок були отримані з умови найкращого узгодження між експериментом і математичним моделюванням. Як стандартні аналітичні методи використовували атомно-силовий мікроскоп і рентгенівський дифракційний аналіз.As a typical Correlated Electron Material, vanadium dioxide was discovered to demonstrate metalinsulator transition at a relatively low temperature. The transition occurs from an insulating monoclinic phase to a metallic tetragonal phase (rutile structure) upon heating with the rearrangement of vanadium ions along an axis of the monoclinic lattice. The phase change corresponds to a colossal resistivity drop by over four orders of magnitude as well as other dramatic property changes, which can be reversible via a natural cooling process. Therefore, vanadium dioxide has attracted extensive attention for its applications in highly sensitive smart devices that can abruptly respond to diverse external stimuli. In recent years, rapid advancement in the fabrication and property modulation of vanadium dioxide has greatly facilitated its applications in many aspects, such as thermal sensing, thermochromics, electronics, and multiple-response mechanics. The optical properties of thin vanadium dioxide films VO2 were researched using the modulation polarimetry technique. For VO2 thin film deposition the two-step method was used. VO2 films were grown on quartz glass substrates by magnetron sputtering of the VO2 target. The films had different modifications of composition, structure, morphology, and optical properties due to the manufacturing technology. The angular dependence of the reflection coefficients of electromagnetic radiation of s- and p- polarizations and their difference for different wavelengths was measured in the paper. The polarization characteristics were simulated by a matrix transformation of the Fresnel formulas. The values of the refractive and absorption indices of the films were obtained from the condition of the best agreement between the experiment and mathematical simulation. Atomic force microscope and X-ray diffraction analysis were used as standard analytical methods

Photoluminescence and structural properties of CdSe quantum dot-gelatin composite films

a b s t r a c t Optical and structural properties of composite films of CdSe quantum dots (QDs) embedded in gelatin matrix have been investigated by photoluminescence (PL), optical absorption and X-ray diffraction (XRD) methods. The optical absorption of the composite in the visible spectral range is found to be determined mainly by light absorption in the QDs. The decrease of the film transparency and the shift of the absorption edge to lower energies observed upon thermal annealing of the films at 140-160 1C are ascribed to the formation of chromophore groups in gelatin matrix. XRD patterns of the composite revealed helix to coil transition in gelatin matrix under thermal annealing of the composite at 100-160 1C. It is found that PL spectra of the composite are dominated by exciton and defect-related emission of the QDs and also contain weak emission of gelatin matrix. It is found that thermal annealing of the composite at 100-160 1C changes PL intensity and produces the shift of the PL bands to lower energies. As the annealed composite was kept in air for several months, the shift of exciton-related PL band position restored partially and the PL intensity increased. It is proposed that the increase of the PL intensity upon the thermal annealing of composite at 140 1C can be used for enhancement of the QDrelated PL. Changes that occurred in the PL spectra of composite are ascribed to structural and chemical transformations in gelatin matrix and at the QD/gelatin interface

XVI Всеукраїнська науково-практична конференцiя студентiв, аспiрантiв та молодих вчених «Теоретичнi i прикладнi проблеми фiзики, математики та інформатики»

This work is concerned with the study of structural characteristics of the amorphous bulk As2S3 glasses doped with Ag (concentration 10% and 15%).Structural studies were carried out using X-ray diffraction. The radial distribution functions of doped and undoped bulk glasses were obtained and analyzed

Stimulated oxygen impurity gettering under ultra-shallow junction formation in silicon

Ultra-shallow junctions were formed by low-energy As ion implantation followed by furnace annealing. It was found that a significant amount of oxygen is redistributed from the silicon bulk to the As-implanted region. Using a marker layer created by implantation of O-18 isotope, it is confirmed that a large number of interstitial oxygen atoms are transferred from the bulk of Si wafer to the surface during dopant activation annealing, which leads to an increase of the surface oxide thickness. Estimation of the oxygen diffusivity in silicon during the 950 degrees C anneal, yields a value close to 1 Chi 10(-10) cm(2) s(-1) which is more than an order of magnitude larger than the literature value which is close to 7 Chi 10(-12) cm(2) s(-1)

The effect of TiO2 crystalline phase on microstructure and optical features of Zn2TiO4 doped with Mn

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