The massive crystal growth of single crystal semiconductors materials has been of fundamental importance for the actual electronic devices industry. As a consequence of this one, we can obtain easily a large variety of low cost devices almost as made ones of silicon. Nowadays, the III-V semiconductors compounds and their alloys have been proved to be very important because of their optical properties and applications. It is the case of the elements In, Ga, As, Sb, which can be utilized for the fabrication of radiation sensors. In this work we present the results obtained from the ingots grown by the Czochralski method, using a growth system made in home. These results include anisotropic chemical attacks in order to reveal the crystallographic orientation and the possible polycrystallinity. Isotropic chemical attacks were made to evaluate the etch pit density. Metallographic pictures of the chemical attacks are presented in this work. Among the results of these measurements, the best samples presented in this work showed mobilities of 62.000 cm2/V*s at room temperature and 99.000 cm2/V*s at liquid nitrogen temperature. Typical pit density was 10,000/cm2. The Raman spectra present two dominant peaks associated at Transversal Optical (TO)- and Longitudinal Optical (LO)-InSb, the first vibrational mode is dominant due to the crystalline direction of the ingots and second one is associated to high defects density.

Light-emitting diodes (LEDs) made from wide band gap semiconductors, such as gallium nitride, are undergoing rapid development. Solid-state lighting with these LEDs is transforming patterns of energy usage and lifestyle throughout the world.

With solid-state lighting gradually taking over from incandescent and fluorescent lighting, light-emitting diodes (LEDs) are very much the focus of research nowadays. This compact review takes a look at LEDs for lighting applications made from wide band gap semiconductors. A very brief history of electric lighting is included for completeness, followed by a description of blue-emitting LEDs that serve as pump sources for all ‘white’ LEDs. This is followed by a discussion on techniques to extract more light from the confines of LED chips through surface patterning. The thermal management of LEDs is perhaps the most important consideration in designing and using LED-based luminaires. This topic is discussed with regard to recent studies on LED reliability. The very promising development of gallium nitride-on-silicon LEDs is examined next followed by a discussion on phosphors for color conversion in LEDs. LED lighting has positively influenced both upscale and downscale illumination markets worldwide. Its societal impact is examined, with the review concluding with a look at efforts to produce LEDs from zinc oxide – a material that holds much promise for the future of solid-state lighting.

Electrophoretic deposition enables the rapid deposition of single wall carbon nanotube films at room temperature. An accurate, reproducible film thickness can be obtained by controlling electric field strength, suspension concentration, and time. To investigate the electrical and mechanical properties of such films, we recorded electric resistance and Young’s modulus using I-V characterization and a nanoindenter, respectively. The measured resistivity of the films varied from 2.14 × 10-3 to 7.66 × 10-3 Ω·cm, and the Young’s modulus was 4.72 to 5.67 GPa, independent of film thickness from 77 to 134 nm. These results indicated that the mechanical and electrical properties of film are comparable with previously reported methods such as layer by layer deposition even though we achieved much higher deposition rates. We also measured the film mass density which is usually unrecorded even though it is an important parameter for MEMS/NEMS device actuation. The film density was found with conventional thickness measurement and Rutherford backscattering spectrometry. It varied from 0.12 to 0.54 g/cm3 as the film thickness increased. This method could be extended to applications of CNT films for flexible electronics or high frequency RF MEMS devices.

At the Great Temple of Tenochtitlan, the archaeologists found hundreds of stone masks considered foreign pieces obtained by commerce, tribute, and pillage. Because of that, they were classified in the main Mesoamerican styles, like the Olmec, Mezcala, Teotihuacan, Mayan, Mixtec and Aztec art. Among them are seven Teotihuacan Style masks found in five offerings. Its presence was explained by other researchers as relics looted by Aztec people from the Teotihuacan site, because the Aztec priests and rulers employed them as sources of power, prestige and mythical links between the City of the Gods and Tenochtitlan. But, are these stone masks from Tenochtitlan really Teotihuacan items? How can we identify which of them came from Teotihuacan and could be relics and which of them not? To solve this problem, we analyze its manufacturing techniques and compare them with lapidary objects from different areas of Teotihuacan, employing experimental archaeology, Optic Microscopy and Scanning Electron Microscopy. As results, we identify two technological patterns: five masks share the tools and techniques of Teotihuacan manufactures but two other masks contrast with them. Interestingly, its technology match with the Tenochcan productions, so, both pieces could be recreations crafted by Aztec artisans during the Postclassic times.

We improve the efficiency of a bottom-emitting red phosphorescent organic light emitting diode (OLED) by the suppression of wave-guided modes in the bottom contact. ITO as bottom contact layer has been substituted by a thin Ti/Au layer. Electromagnetic simulation results of both devices predict the absence of TE polarized guided contact modes by the use of 10 nm Au as bottom electrode. We measured an improved outcoupling of light which overcompensates absorption losses of the Ti/Au layer in the measured emission cone. By the use of 1 nm Ti as undercoat, a continuous Au film of 8 nm thickness could be realized with an improved transmittance for long wavelengths (λ > 550 nm). As a consequence of fewer lateral guided modes, the external quantum efficiency (EQE) has been enhanced from 11.5 % of the standard device to 14 % of the device with the Ti/Au electrode.

Cellulose nanofibers (Cel-F) were extracted by a simple and harmless Star Burst (SB) method, which produced aqueous cellulose-nanofiber solution just by running original cellulose beads under a high pressure of water in the synthetic SB chamber. By optimizing the SB process conditions, the cellulose nanofibers with high aspect ratios and the small diameter of ∼23 nm were obtained, which was confirmed by transmission electron microscopy (TEM). From the structural analysis of the Cel-F/PVA composite by the scanning electron microscopy (SEM), it was found that the Cel-F were homogeneously dispersed in the PVA matrix. Considering the high molecular compatibility of the cellulose and PVA due to the hydrogen bonding, a good adhesive interface could be expected for the Cel-F and the PVA matrix. The influences of the morphological change in Cel-F on the mechanical properties of the composites were analysed. The Young’s modulus rapidly increased from 2.2 GPa to 2.9 GPa up to 40 SB treatments (represented by the unit Pass), whereas the Young’s modulus remained virtually constant above 40 Pass. Due to the uniform dispersibility of the Cel-F, the Young’s modulus of the 100 Pass composite at the concentration of 5 wt% increased up to 3.2 GPa. The experimental results corresponded well with the general theory of the composites with dispersed short-fiber fillers, which clearly indicated that the potential of the cellulose nanofibers as reinforcement materials for hydrophilic polymers was sufficiently confirmed.

Inkjet printing is a well-accepted deposition technology for functional materials in the area of printed electronics. It allows the precise deposition of patterned functional layers on both, rigid and flexible substrates. Furthermore, inkjet printing is considered as up-scalable technology towards industrial applications. Many electronic devices manufactured with inkjet printing have been reported in the recent years. Some of the evident examples are capacitors, resistors, organic thin film transistors and rectifying Schottky diodes. [1, 2, 3] In this paper we report on the manufacturing of an inkjet-printed metal-insulator-semiconductor (MIS) diode on flexible plastic substrate. The structure is comprised of an insulating and a polymeric semiconducting layer sandwiched between two silver electrodes. The current vs. voltage characteristics are rectifying with rectification ratio up to 100 at |4 V|. Furthermore, they can carry high current densities (up to mA/cm2) and have a low capacitance which makes them attractive for high frequency rectifying circuits. They are also an ideal candidate to replace conventional Schottky diodes for which the fabrication remains a challenge. This is because inkjet printing of Schottky diodes require additional processing steps such as intense pulsed light sintering (IPL sintering) [4] or post-treatments at high temperatures. The deposition of two different metal layers using inkjet printing e.g. Cu or Al with Ag is possible. However, the mentioned post treatment technologies might be incompatible with the already existing layer stack– e.g. it could degrade the organic semiconductor or can damage insulator which in this case is present in the MIS diode architecture.

Electrochemical Impedance Spectroscopy (EIS) and the Parallel Electrical Dielectric Response Analysis (PEDRA) application were used to describe the inner barrier oxide films on irradiated zirconium alloys. This is achieved with minimal surface preparation and without disturbing the outer porous oxide. These two distinguishable inner and outer oxide layers result from a growth-fracture oxidation mechanism. Key to success of the EIS technique in describing the barrier oxide layer are: 1) the model and procedure used to fit EIS spectra, 2) the validation of the fit, and 3) converting circuit parameters (R, C and n) into physical attributes of the barrier oxide.

The barrier oxide is defined as the inner-dense layer adjacent to the metal-oxide interface. The integrity of barrier oxide is thought to effect both oxidation (i.e. access of water to the interface), and hydrogen pickup (i.e. failure hydrogen to escape away from the interface). Using EIS and the PEDRA application, the barrier oxide is described in terms of multiple independent dielectric responses to yield a unique 'micro-macro' picture of the barrier oxide that can be used to explain observed H pickup behavior.

Bone is a natural protein (collagen)-mineral (hydroxyapatite) nanocomposite with hierarchically organized structure. Our previous work has demonstrated orientational differences in stoichiometry of hydroxyapatite resulting from orientationally dependent collagen-mineral interactions in bone. The nature of these interactions has been investigated both through molecular dynamics simulations as well as nanomechanical and infrared spectroscopic experiments. In this study, we report experimental studies on human cortical bone with osteogenesis imperfecta (OI), a disease characterized by fragility of bones and other tissues rich in type I collagen. About 90% of OI cases result from causative variant in one of the two structural genes (COL1A1 or COL1A2) for type I procollagens. OI provides an interesting platform for investigating how alterations of collagen at the molecular level cause changes in structure and mechanics of bone. Fourier transform spectroscopy, electron microscopy (SEM), and nanomechanical experiments describe the structural and molecular differences in bone ultrastructure due to presence of diseases. Photoacoustic-Fourier transform infrared spectroscopy (PA-FTIR) experiments have been conducted to investigate the orientational differences in molecular structure of OI bone, which is also compared with that of healthy human cortical bone. Further, in situ SEM static nanomechanical testing is conducted in the transverse and longitudinal directions in the OI bone. Microstructural defects and abnormities of OI bone were ascertained using scanning electron microscopies. These results provide an insight into molecular basis of deformation and mechanical behavior of healthy human bone and OI bone.

Molybdenum silicides and borosilicides are promising structural materials for advanced power plants. A major challenge, however, is to simultaneously achieve high oxidation resistance and acceptable mechanical properties at high temperatures. For example, molybdenum disilicide (MoSi2) has excellent oxidation resistance and poor mechanical properties, while Mo-rich silicides such as Mo5Si3 (called T1) have much better mechanical properties but poor oxidation resistance. One approach is based on the fabrication of MoSi2−T1 composites that combine high oxidation resistance of MoSi2 and good mechanical properties of T1. Another approach involves the addition of boron to Mo-rich silicides for improving their oxidation resistance through the formation of a borosilicate surface layer. In particular, Mo5SiB2 (called T2) phase and alloys based on this phase are promising materials.

In the present paper, MoSi2−T1 composites and materials based on T2 phase are obtained by mechanically activated self-propagating high-temperature synthesis (MASHS). To obtain denser products, the so-called SHS compaction (quasi-isostatic pressing of hot combustion products) has been employed. Thermal analysis has shown that SHS compaction significantly improves the oxidation resistance. Self-sustained combustion of Mo/Si/B mixtures for the formation of T2 phase becomes possible if the composition is designed for adding a more exothermic reaction of MoB formation. These mixtures exhibit spin combustion. Oxidation resistance of the obtained multi-phase Mo−Si−B materials is independent on the concentration of Mo phase in the products. The “chemical oven” technique has been used to obtain a single Mo5SiB2 phase and an alloy consisting of α-Mo, Mo5SiB2, and Mo3Si phases.

A scanning force microscope for in situ nanofocused X-ray studies (SFINX) has been developed which can be installed on diffractometers at synchrotron beamlines allowing for the combination with various techniques such as coherent X-ray diffraction and fluorescence. The capabilities of this device are demonstrated on Cu nanowires and on Au islands grown on sapphire (0001). The sample topography, crystallinity, and elemental distribution of the same area are investigated by recording simultaneously an AFM image, a scanning X-ray diffraction map, and a fluorescence map. Additionally, the mechanical response of Au islands is studied by in situ indentation tests employing the AFM-tip and recording 2D X-ray diffraction patterns during mechanical loading.

We have investigated surface modification methods for avalanche photodiodes using dielectrics deposited by atomic layer deposition (ALD). Arrays of mesa GaN APDs were fabricated, and ALD Al2O3 was used for sidewall passivation prior to completing the APD array. The use of ALD Al2O3 in this manner was observed to result in a large average improvement in APD dark current when compared with devices using more conventional SiO2 passivation layers produced by chemical vapor deposition. Co-processed metal-oxide-semiconductor (MOS) capacitors fabricated with the same passivation layers show significant improvement in electrical interface quality for devices with ALD Al2O3.

This contribution shows the results of a study carried out in order to determinate the deterioration mechanisms suffered by stucco masks from the important archaeological Mayan site of Edzná, Campeche, México; due to their long exposition to the tropical environment of the zone. Stratigraphic analysis of fragments from the masks containing pigments and surface neoformation products, were analyzed by optical microscopy and scanning electron microscopy coupled to a secondary X-ray emission system. Crystalized salts mineral composition were characterized by X-ray diffraction. Also, during the study, environmental parameter like temperature and relative humidity were monitored in site. Results indicate that stuccos mineral matrix is formed by calcareous materials, covered by films with variable proportions of ferrous materials (red, ochre and yellow colors) and rich carbon content (black color). Compounds were associated to blue and green colors. Al these materials showed a high level of deterioration because of differential forces caused by stucco and deposits of environmental soluble salts during dissolution crystallization cycles caused by humidity differences between stucco and environmental as a consequence of their particular exposure conditions.

A novel allergy biosensor is designed and fabricated by using thin film bulk acoustic resonator (TFBAR) devices with shear mode ZnO piezoelectric thin films. To fabricate TFBAR devices, the off-axis RF magnetron sputtering method for the growth of piezoelectric ZnO piezoelectric thin films is adopted. The influences of the relative distance and sputtering parameters are investigated. In this report, the piezoelectric ZnO thin films with tilting angle are set by controlling the deposition parameters. The properties of the shear mode ZnO thin films are investigated by X-ray diffraction and scanning electron microscopy. The frequency response is measured using an HP8720 network analyzer with a CASCADE probe station. The resonance frequency of the shear mode is 796.75 MHz. The sensitivity of the shear mode is calculated to be 462.5 kHz·cm2/ng.

As an emerging manufacturing technique, nanoimprint lithography (NIL) can fabricate micro and nanoscale features of microfluidic devices at very high accuracy and reliability. In high-temperature TNIL process, a polymer melt such as polymethyl-methacrylate (PMMA) is heated beyond the melting temperature so that it behaves predominantly as a fluid during the imprint process. The process parameters such as pressure, temperature, and material properties play critical roles in the NIL process. In this work, the process of thermal nanoimprint lithography (TNIL) is studied computationally with emphasis on the effect of soft-mold deformation on polymer melt flow and finished result by-way-of fluid-structure interaction (FSI) technology. Process is assumed isothermal at 180 °C. Applications of this modeling technique range from micro- and nano-patterns used in micro-channels for biomedical devices to other applications such as biological/particle sensors or super-hydrophobic surfaces. The simulation result is compared to experimental results, and traits observed in TNIL done with soft mold are supported and explained through numerical results.

In this work the thermal and kinetic analysis of the cooling and solidification of a near eutectic Al-Cu alloy is performed using inverse thermal and solidification kinetics analysis. The Fourier thermal analysis is applied to experimental cooling curves to obtain data on solid fraction evolution and latent heat of solidification. Inverse thermal analysis is applied to calculate the global heat transfer coefficients that allow correct simulation of the cooling of experimental probes. The free growth method is used to obtain the eutectic growth coefficients. All the obtained parameters are feed into a heat transfer-solidification kinetics model to validate the methodology and results generated from this work. It is found a relatively good agreement between experimental and predicted cooling curves which suggest that this methodology could be used to generate useful information needed to simulate eutectic solidification.

Crystalline TiO2 nanoparticles were produced by scalable flame spray pyrolysis of organometallic solutions. A protocol is presented for the optimized functionalization of these particles with fluorescein isothiocyanate (FITC), an important biomedical dye via a lysine linker. The pH, stoichiometry and time for lysine reaction were determined for highest dye loading and minimized degree of polylysine formation. Acidic reaction conditions, low lysine concentration and short reaction times were found to meet this aim. The resulting particles were used for imaging single neurons, showing high fluorescence emission and ability for the particles to diffuse into small neuron structures such as dendrites.