Electronic Materials

Cu 2 O/ZnO:Al (AZO) and Cu 2 O/ZnO/AZO heterojunctions have been deposited on glass substrates by a unique three-step pulsed laser deposition process. The structural, optical, and electrical properties of the oxide films were investigated before their implementation in the final device. X-ray diffraction analysis indicated that the materials were highly crystallized along the c-axis. All films were highly transparent in the visible region with enhanced electrical properties. Atomic force and scanning electron microscopies showed that the insertion of a ZnO layer between the Cu 2 O and AZO films in the heterojunction enhanced the average grain size and surface roughness. The heterojunctions exhibited remarkable diode behavior and good rectifying character with low leakage current under reverse bias. The presence of the ZnO interlayer film significantly reduced the parasitic and leakage currents across the barrier, improved the quality of the heterostructure, made the energy band between AZO and Cu 2 O layers smoother, and eliminated the possibility of interface recombination, leading to much longer electron lifetime.

Microscopy and Microanalysis) facilities at IISc for providing the usage of FIB and TEM, respectively. Special acknowledgement to Mrs. Suma for teaching me FIB and always being there for all the help I needed. I am grateful to my colleague Sandeep and my lab mate Raja for their valuable contribution to the Ni/Sn RT (room temperature) ageing experiment of 2.5 years. I thank my friend Rajib Kalsar for attempting several EBSD scans on my samples; however, the scans could not give successful results. I thank my all lab mates: Hari,

We have modeled diffusion of H in a two-step Si 3 N 4 passivation process invoking the concept of "storage" of H. The H stored during nitridation is redistributed during a subsequent anneal. The modeling results agree with this hypothesis, and the conclusions also appear to concur with the observations

This paper describes some applications of PVSCANan instrument developed for rapid characterization of photovoltaic (PV) materials and devices. It measures defect distribution, reflectance, and external and internal responses of light beam induced current at two wavelengths of optical excitation.

The thermodynamic optimization of the Ni-Sn-Bi ternary system was performed using the Calphad method and experimental data obtained by Differential Scanning Calorimetry and Scanning Electron Microscopy. The ternary phase was described using a three-sublattice model. The previously reported new ternary compound and the solubility of the third element in two binary systems (Bi in Ni-Sn and Sn in Bi-Ni) were included in the optimization. Four isothermal sections were calculated using Thermi-Calc software and compared with the experimentally obtained ones. A miscibility gap in the ternary system was found at 1610 K.

Phase equilibria were studied in the system Ni-Sn-Bi at 733 and 903 K. For this purpose, 30 ternary samples were synthesized using intimately mixed powders. After annealing in quartz ampoules and quenching, all alloys were analysed by scanning electron microscope. Differential thermal analyses (DTA) were done with specimens having chemical compositions near to the expected ternary Bi-Sn eutectic point. Isothermal sections of ternary system at 733 and 903 K were constructed. The phase equilibria between the liquid and the solid phases ((Ni), NiBi, Ni 3 Sn 2 and Ni 3 Sn 4 ) appeared to be inclined towards the Bi-corner at all temperatures. A formerly unknown ternary compound with approximate formula Ni 7 Sn 2 Bi and chemical composition (in mole fractions) X Ni = 0.66 ± 0.03, X Sn = 0.21 ± 0.02 and X Bi = 0.13 ± 0.02 was observed by scanning electron microscopy but it could not be identified by X-ray diffraction analyses.

HgCdTe remains the material of choice for high-performance infrared (IR) detectors due to its tunable direct bandgap energy corresponding to the IR spectral region, and the advancement of HgCdTe materials growth and processing technologies. Accurate knowledge of the HgCdTe optical absorption coefficient is important for IR detector design, layer screening, and device analysis. The spectral response for IR detectors is dependent on optical absorption above the bandgap energy, where much of the study of absorption coefficient in HgCdTe has focused on the bandtail region. In this work, the optical absorption coefficient was studied by theoretical bandstructure calculations and experimental measurements on HgCdTe layers using techniques of IR spectroscopic ellipsometry and IR transmission. The theoretical and experimental results suggest that the absorption coefficient between 600 cm Ϫ1 and 5,000 cm Ϫ1 is related to energy relative to bandgap with a fractional exponent between 0.6 and 1, rather than the previously used expressions relating to a parabolic or hyperbolic bandstructure. The fitting parameters for Hg 1-x Cd x Te with x ϭ 0.22-0.60 are presented to develop a model for the optical absorption coefficient spectra. The calculated detector spectral response using the new and previously reported absorption coefficient models suggests that next generation IR detectors employing multilayer structures with graded compositional profiles will likely benefit from this new model.

This paper reports the further development of the model for the analysis of FTIR transmission spectra from the dual-color Hg 1-x Cd x Te (MCT) structures for the constituent layer thickness and alloy composition. The previously reported model 1 was shown to suffer from excessively high uncertainty in the provided individual layer thickness and low convergence rate for some types of structures, attributed primarily to inaccuracies in the model representation of the MCT dielectric function. Since last report, we have substantially improved the FTIR analysis accuracy by developing a better MCT dielectric function approximation, which is based on the interpolation of the measured spectroscopic ellipsometry (SE) experimental spectral dielectric functions at few discrete alloy compositions. Based on this, the optical model for graded layers was also created and calibrated against the traditional FTIR data reduction technique. The new model was shown to produce the most accurate fits to the experimental FTIR transmission spectra from single-and two-color detector structures, and has demonstrated a better convergence rate. The new model was tested to predict both band cutoff wavelengths for the actual two-color MWIR/LWIR SUMIT detectors. We have demonstrated that the model prediction from as-grown structures was in good agreement with the actual two-color device data, as measured on performance evaluation chips (PECs), thus validating the modeling technique for routine postgrowth wafer screening.

Anomalous diffusion profiles of Ag in single crystalline CdTe were observed using the radiotracer 111 Ag. The diffusion anneals were performed at 800 K under Cd or Te vapor and in vacuum with low Ag concentrations. The measured Ag profiles directly reflect the distribution of the self-interstitials and vacancies of the Cd sublattice and are the result of chemical self-diffusion which describes the variation of the deviation from stoichiometry of the binary crystal as a function of depth and time. It turned out that the spread of the Ag dopant essentially is determined by the drift of the charged defects within the electric field caused by the distribution of the extrinsic and intrinsic defects.

Metallization of high-T c superconductors using low resistivity metal oxides and Cu-Ge alloys has been investigated on high quality pulsed laser deposited epitaxial YBa2Cu3OT_ x (YBCO) films. Epitaxial LaNiO 3 (LNO) thin films have been grown on YBCO films at 700~ using pulsed laser deposition. The specific resistivity of LNO was measured to be 50 p~-cm at 300K which decreases to 19 p~-cm at 100K indicating good metallicity of the LNO films. The contact resistance of LNO-YBCO thin film interface was found to be reasonably low (of the order of 104 ~2-cm 2 at 77K) which suggests that the interface formed between the two films is quite clean and LNO can emerge as a promising metal electrodematerial to YBCO films. A preliminary investigation related to the compatibility of Cu3Ge alloy as a contact metallization material to YBCO films is discussed. The usage of other oxide based low resistivity materials such as SrRuO 3 (SRO) and SrVO 3 (SVO) for metallization ofhigh-T YBCO superconductor films is also discussed.

Much recent attention has been paid to elevating the barrier height of contacts to InP and Ino.5~Gao.47As via the formation of a thin, intermediate layer between the semiconductor and a conventionally deposited, highly conductive contact layer. Here, we report on the use of thin (-200A) excimer laser photodeposited Cd as an interlayer between these semiconductors and Au overlayers in order to raise the barrier height of the resulting diodes. Current-voltage measurements of ideal Schottky diodes fabricated using this process yield barrier heights of 0.70 eV and 0.55 eV to InP and Ino.53Gao.47As, respectively. The photodeposition process has been integrated with conventional clean room processing resulting in Au/Cd/Ino.53Gao.47As transistors with high transconductances (-200 mS/mm) and operating frequencies (fmax ~ 30 GHz). X-ray photoelectron spectrosco)y of thin Cd photodeposits on InP shows that the process produces an interfacial (-10Athick) Cd-InP reaction zone covered by metallic Cd.

The nickel-copper mixed ferrite nanoparticles [Cu 1Àx Ni x Fe 2 O 4 (x = 0, 0.5, 1)] NPs were prepared a by combustion method using Aloe barbadensis extract as a green reducing agent. The structural, functional, morphological, optical, magnetic, electrochemical properties of the sample were investigated using xray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, energy-dispersive x-ray spectroscopy, ultraviolet-visible (UV-Vis) spectrophotometry, photoluminescence, vibrating sample and cyclic voltammetry. The XRD patterns showed that all compositions with a cubic spinel structure and a crystallite size of 52 nm were reduced to 29 nm after nickel addition in copper ferrite and 35.85 nm for nickel ferrite. The UV-Vis absorption spectrum shows that the nickel-substituted copper ferrite band energy (E g ) increases as the crystallite size decreases. Measurements of magnetization obtained at room temperature revealed a soft ferromagnetic behaviour and saturation magnetization, coercivity value increased with the substitution of nickel. The maximum specific capacitance of 114 F g À1 was obtained at the scan rate of 5 mV s À1 for copper-nickel mixed ferrite NPs. A study of antibacterial activity against Escherichia coli, Klebsilla pneumonia, Staphylococcus aureus, and Bacillus subtilis using a well-diffusion method was performed. Nickel substitution on the copper spinel ferrite NPs revealed a major influence on structural, optical, magnetic, electrochemical and magnetic properties of the product obtained.

The nickel-copper mixed ferrite nanoparticles [Cu 1Àx Ni x Fe 2 O 4 (x = 0, 0.5, 1)] NPs were prepared a by combustion method using Aloe barbadensis extract as a green reducing agent. The structural, functional, morphological, optical, magnetic, electrochemical properties of the sample were investigated using xray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, energy-dispersive x-ray spectroscopy, ultraviolet-visible (UV-Vis) spectrophotometry, photoluminescence, vibrating sample and cyclic voltammetry. The XRD patterns showed that all compositions with a cubic spinel structure and a crystallite size of 52 nm were reduced to 29 nm after nickel addition in copper ferrite and 35.85 nm for nickel ferrite. The UV-Vis absorption spectrum shows that the nickel-substituted copper ferrite band energy (E g ) increases as the crystallite size decreases. Measurements of magnetization obtained at room temperature revealed a soft ferromagnetic behaviour and saturation magnetization, coercivity value increased with the substitution of nickel. The maximum specific capacitance of 114 F g À1 was obtained at the scan rate of 5 mV s À1 for copper-nickel mixed ferrite NPs. A study of antibacterial activity against Escherichia coli, Klebsilla pneumonia, Staphylococcus aureus, and Bacillus subtilis using a well-diffusion method was performed. Nickel substitution on the copper spinel ferrite NPs revealed a major influence on structural, optical, magnetic, electrochemical and magnetic properties of the product obtained.

Vanadium pentoxide (V2O5) nanorods were prepared on various substrates by simple hydrothermal method. The structural characterizations of V2O5 nanorods (NRs) have been studied by using X-ray diffraction analysis. The influence of the different substrates on the surface morphology of V2O5 NRs was investigated by field emission scanning electron microscopy (FESEM) technique. The results show that the preferred orientation along (001) plane. Raman spectra indicate that glass substrate has optimum results due to the size and number of the nanorods with lower defects. It can be found from the absorbance of the glass substrate increases ccompared with the other substrate

This paper presents the study of oxide film heterojunction made of CuAlCrO 2 and ZnO:Al (AZO) deposited on fused quartz by sol-gel spin coating. Transmission electron microscopy (TEM) analysis has showed that the solvent, which was used to prepare the AZO sol, affects the thickness and planarity of the applied layers and the grain size of the polycrystalline film. The formation of a fine-grained structure of AZO films (grain size is up to 12 nm) leads to the formation of a smoother p-CuAlCrO 2 / n-AZO heterojunction. X-ray diffraction (XRD) analysis and TEM have revealed that the heterojunction was formed by AZO polycrystals, which orient axes [101] and [100] against the [101] and [006] directions in CuAlCrO 2 polycrystals. The optical transmission of the heterojunction in the visible range reached 70 %. The current-voltage (I-V) characteristics of p-CuAlCrO 2 / n-AZO corresponds to a diode one in the range from 4 up to 4 V. For the large values of the reverse bias, an increase in the leakage current is observed, which is associated with tunneling breakdown of heterojunction. The ideality factor of fabricated p-CuAlCrO 2 / n-AZO heterojunction is more than 2, which indicates the mechanisms of conductivity by defect-levels. In additional, it has been observed the response of the current-voltage characteristics to the green illumination (532 nm) of the diode that is associated with indirect band-gap absorption in CuAlCrO 2. The impact of the white LED illumination had no effect on the current-voltage characteristics of the diode.

4H-SiC silicon carbide (SiC) Schottky diodes, with a 25 lm thick n-type epitaxial active layer and a very thin front electrode contact are studied and proposed for the detection of low energetic ions. For a first evaluation of the detection properties of the SiC detectors, a standard alpha emitting radiation source was used obtaining an energy resolution of 0.85% at 5.15 MeV energy. Then the devices were employed to monitor low energetic alpha particles. From these tests it was found that the 4H-SiC diodes are able to monitor the alpha particles backscattered by different single and multilayers metallic targets (Au, Ag, Cu on Si substrates) in the energy range between 300 keV and 600 keV. In this energy range a linear energy response and a good energy resolution, close to those of a traditional commercial silicon detector, were obtained. The possibility to use these detectors for material analysis and for plasma monitoring is also discussed.

Herein, teh first TEMPprincipal calculations and Monte Carlo Simulation (MCS) were performed to investigate teh magnetic and magneto-caloric properties of PrSi compound. Teh partial magnetic moment of Pr (m Pr ), and teh exchange interactions parameters (J 1 , J 2 ) are found to be m Pr = 2.8 µ B , J 1 = 1.707 meV and J 2 = 1.312 meV, respectively. Through teh MCS, it was found dat teh Curie temperature value (T c ) from ferromagnetic to paramagnetic state is T c = 55 K, which is in good agreement wif teh experimental value which is 54 K. Moreover, it was established dat a slight increase in teh applied magnetic field leads to a high increase in teh magnetic entropy from 4.4 J/kg K for h = 1 T to 13.7J/kg K for h=5 T. Furthermore, teh values of adiabatic temperature change and relative cooling power (RCP) obtained for h = 5 T were found to be 3.6 K and 550 J/kg, respectively.

Transparent orthorhombic molybdenum trioxide (a-MoO 3 ) thin films were prepared on glass substrates by sol-gel dip coating technique of a quality comparable to those prepared by more sophisticated techniques regarded as very costly and difficult to carry out. The prepared films were annealed in air at different temperatures in the range of 150-350°C. X-ray diffraction analysis of the films prepared at 250°C and 350°C confirmed the formation of a singlephase of MoO 3 in an orthorhombic crystal system (a-MoO 3 ). Scanning electron microscopy of the films annealed at 350°C indicated a stack of nano-layers with thickness of approximately 30 nm-40 nm. Fourier transform infrared transmittance analysis revealed the Mo=O stretching vibration, which is an indicator of the layered orthorhombic MoO 3 phase. Energy dispersive x-ray analysis confirmed the existence of Mo and O in the deposited films. A maximum optical transmittance of 82% in the visible range was obtained from the films annealed at 350°C. The band gap value of the films was evaluated and it was in the range of 3.28 eV-3.40 eV. The obtained results showed that the a-MoO 3 thin films prepared at 350°C exhibit good structural, chemical, and optical properties, which might be of interest to the photovoltaic and optoelectronic devices.

The growth of higher manganese silicide (HMS) films on monocrystalline silicon (100) has been investigated. This growth was performed by solid-state reaction. Using electron beam evaporation a single layer of manganese was deposited on a silicon substrate. The samples so prepared were heat treated in a classical furnace under vacuum. A highly textured film was obtained after treatment at 890°C for 18 h. The obtained HMS was identified as Mn 15 Si 26 . The texture relationship is (105) [100] Mn 15 Si 26 i (100) [100] Si. Mn 15 Si 26 has a tetragonal cell; hence, the angle between the c-axis and the normal of the sample surface is 60°. Since this value is far from 0°and 90°, a large transverse thermoelectric effect is expected in these samples. As a consequence the HMS films could be used in anisotropic electromotive force-thermogenerators.

Mg 2 Si thin and ultra-thin films are grown on silicon (Si) substrates by performing heat treatments of Magnesium (Mg) layers deposited on Si (100), using radio frequency (RF)-sputtering and molecular beam epitaxy (MBE) techniques. In order to investigate the effect of annealing parameters on the formation of Mg 2 Si thin films, we conducted heat treatments under vacuum for some samples and in an argon gas atmosphere for others. X-ray diffraction (XRD) analysis of the thin films annealed in both environments confirms the formation of polycrystalline Mg 2 Si. This characterization also reveals that the formation of this compound depends on duration and pressure for the vacuum annealing and on temperature for the argon gas atmosphere annealing. Here, we report that the vacuum annealing is a good choice for Mg 2 Si thin film formation because the low temperature of the process is condusive to silicon technology. Some optimum parameters for obtaining Mg 2 Si thin films are proposed in this paper. Auger electron spectroscopy (AES) characterization technique confirms the formation of Mg 2 Si ultra-thin films at an annealing temperature of 200°C and under an ultra-high vacuum (UHV). In addition, scanning tunneling microscopy (STM) characterization indicates a nanosized grain formation of this compound with average size of approximately 20-40 nm.

This paper presents a study of electron scattering in damascene-processed Cu interconnects. To understand the leading electron-scattering mechanism responsible for the size effect, Cu interconnects with varying physical widths, 80-750 nm, were made, and their resistivity characterized as a function of temperature, ranging from liquid He temperature (4.2 K) to 500 K. The resulting data suggest that surface scattering, contrary to expectations, was not the primary cause of the size effect observed in this investigation. Surface scattering was found to weaken with decreasing line width. Further analysis leads to the conclusion that a substantial fraction of the size effect originates from impurity content scaling inversely with width in these samples.

This study presents the impact of gate length scaling on analog and radio frequency (RF) performance of a self-aligned multi-gate n-type In 0.53 Ga 0.47 As metal oxide semiconductor field effect transistor. The device is fabricated using a self-aligned method, air-bridge technology, and 8 nm thickness of the Al 2 O 3 oxide layer with different gate lengths. The transconductance-to-normalized drain current ratio (g m /I D ) method is implemented to investigate analog parameters. Moreover, g m and drain conductance (g D ) as key parameters in analog performance of the device are evaluated with g m /I D and gate length variation, where g m and g D are both showing enhancement due to scaling of the gate length. Early voltage (V EA ) and intrinsic voltage gain (A V ) value presents a decreasing trend by shrinking the gate length. In addition, the results of RF measurement for cut-off and maximum oscillation frequency for devices with different gate lengths are compared.

This study presents the impact of gate length scaling on analog and radio frequency (RF) performance of a self-aligned multi-gate n-type In 0.53 Ga 0.47 As metal oxide semiconductor field effect transistor. The device is fabricated using a self-aligned method, air-bridge technology, and 8 nm thickness of the Al 2 O 3 oxide layer with different gate lengths. The transconductance-to-normalized drain current ratio (g m /I D ) method is implemented to investigate analog parameters. Moreover, g m and drain conductance (g D ) as key parameters in analog performance of the device are evaluated with g m /I D and gate length variation, where g m and g D are both showing enhancement due to scaling of the gate length. Early voltage (V EA ) and intrinsic voltage gain (A V ) value presents a decreasing trend by shrinking the gate length. In addition, the results of RF measurement for cut-off and maximum oscillation frequency for devices with different gate lengths are compared.

In this study, the effect of carbon nanotubes (CNTs) at various concentrations (0.05, 0.06, 0.08, and 0.1 wt.%) on the electro optical properties of liquid crystal (LC) has been studied. Results show that the threshold voltage, frequency response, rise time and response time of pure LC optical switch decreased with the concentration of CNTs. LC doped with 0.08 wt.% of CNTs revealed the most significant enhancement, resulting in a response time reduction of about 94%, confirmed that the doped LC is the best for the optical switch applications.

A proposed eleven-parameter three-body shell model is used to study the lattice dynamical properties such as phonon dispersion relations along high symmetry directions, phonon density of states, variation of specific heat and Debye characteristic temperature with absolute temperature, elastic constants and related properties for III-V semiconductor AlSb, GaSb and their mixed semiconductor Ga 1-x Al x Sb having zinc-blende structure. We found an overall good agreement with the available experimental and theoretical results available in the literature. Elastic constants • Lattice dynamics • Mixed semiconductor • Phonons B A. K. Kushwaha

For display applications, high current and large on/off current ratio are pursued for driving and switching transistors. In this article, a thin film transistor (TFT) device incorporating a buried electrode is proposed, which enables to increase the driving current due to the reduction of the channel length, with the channel length only at the drain side. This lateral short channel TFT enables to increase the on-current when maintaining the field Accepted manuscript / Final version effect mobility, in comparison to our experimental short-channel vertical TFT structure. Another advantage of the proposed structure lies in the suppression of the Schottky barrier at the source and drain contacts when using high-work-function source/drain contacts for an N-type TFT, with an increased on/off current ratio reaching approximately 10 6 . The suppression of Schottky barrier at source/drain has been verified by the contact resistance measurements. Even though high driving current is obtained, the off-current is still high due to the weakened electric field at source/drain sides and needs to be further optimized.

For display applications, high current and large on/off current ratio are pursued for driving and switching transistors. In this article, a thin film transistor (TFT) device incorporating a buried electrode is proposed, which enables to increase the driving current due to the reduction of the channel length, with the channel length only at the drain side. This lateral short channel TFT enables to increase the on-current when maintaining the field Accepted manuscript / Final version effect mobility, in comparison to our experimental short-channel vertical TFT structure. Another advantage of the proposed structure lies in the suppression of the Schottky barrier at the source and drain contacts when using high-work-function source/drain contacts for an N-type TFT, with an increased on/off current ratio reaching approximately 10 6 . The suppression of Schottky barrier at source/drain has been verified by the contact resistance measurements. Even though high driving current is obtained, the off-current is still high due to the weakened electric field at source/drain sides and needs to be further optimized.

Hg1−xCdxTe films with 2 in. diameters have been grown by molecular beam epitaxy on GaAs (100) substrates. These films were grown in both the (100) and (∼(111)) B crystallographic orientations and in both conduction types. They were characterized by in situ electron diffraction, infrared absorption, and van der Pauw dc Hall measurements. Their surfaces were shiny and mirrorlike from center to edge. The Cd concentrations (x) of these films were very uniform, exhibiting standard deviations (Δx) as low as 0.7% of the mean (x̄). Their thicknesses also were uniform within 0.6%. These films were completely uniform in their conduction types; that is, the n-type films were entirely n type, and likewise for the p-type films. The Hall mobilities of these films show them to be of high quality, with values as high as 6.7×102 cm2 V−1 s−1 for the p-type (x=0.22) and 1.8×105 cm2 V−1 s−1 for the n-type films (x=0.21). These results represent an important achievement toward the future of infrared det...

A phase-heterogeneous ceramic based on layered calcium cobaltite Ca 3 Co 4 O 9+δ was prepared by solid-phase reactions followed by hot pressing. The phase composition, microstructure, electrical conductivity, and thermoelectromotive force (thermo-emf) of the ceramic were studied, and the power factor (P) was calculated. Hot pressing allows preparation of a high-density ceramic with high electrical conductivity, and the phase heterogeneity considerably increases its thermo-emf coeffi cient, which in total can be considered as a procedure for preparing a ceramic with improved thermoelectric characteristics. The ceramic of the nominal composition Ca 3 Co 4.4 O 9+δ , containing an impurity Co 3 O 4 phase, has the highest power factor (P 1100 = 427 μW m -1 K -2 ), which is 1.5 times higher than that of Ca 3 Co 4 O 9+δ (P 1100 = 280 μW m -1 K -2 ) and more than 4 times higher than that of the low-density ceramic Ca 3 Co 4 O 9+δ prepared by the traditional solid-phase method.

The chemical coupling of NiO nanostructures with thermally treated multiwall carbon nanotubes (MWCNTs) is not reported as it provides an enhanced dispersion of composite material in water. The dispersion of MWCNTs has been considered a big challenge. For this purpose, we first thermally treated MWCNTs at 1000°C in air for 30 min. Then, thermally treated MWCNTs were chemically coupled with NiO nanostructures by a hydrothermal method. The material characterization in terms of structure, morphology, and composition is well studied by different analytical techniques. The NiO composite (sample 2) with highest weight of MWCNTs had a leaf-like morphology and it exhibits a cubic phase of NiO. Cyclic voltammetry (CV) was used to study the electrochemical activity of prepared composite material towards the oxidation of uric acid in the phosphate buffer solution of pH 7.0. Sample 2 showed a well-behaved anodic peak with enhanced peak current and exhibited a linear range from 0.01 mM to 2.5 mM for uric acid with a low limit of detection 0.001mM. Sample 2 was found to be very selective under the environment of competing interferents such as urea, glucose, lactic acid and ethanol. This sample exhibits significant stability, thus it is a potential protocol for the monitoring of uric acid from real samples. This study provides a low-cost platform for the fabrication of efficient materials for various applications such as batteries, fuel cells and water splitting.

The Eu 3+ -activated double molybdate red phosphor, LiEuMo2O8 was prepared by a sol-gel process using inorganic salts as starting materials. A precursor prefired at 500 °C for 240 min was subsequently annealed at 600 °C for 240 min in Ar. The crystal structure, surface morphology and luminescent properties were analyzed by an X-ray diffractometer, a field emission scanning electron microscope and a fluorescent spectrophotometer. The obtained LiEuMo2O8 shows a strong excitation band near 395 and 466 nm and intensely red-emission lines at 616 nm corresponding to the 5 D0 ˧ 7 F2 transitions on Eu 3+ at 395 nm of light excitation.

Bis-(morpholinodithiato-s,s¢)-Cu-Zn was synthesized as a single solid source precursor and characterized using particle-induced x-ray emission (PIXE), Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC). Cu-Zn-S thin film was deposited on sodalime glass substrate using metal organic chemical vapor deposition (MOCVD) technique at temperatures ranging from 360°C to 450°C. The thin films were characterized using Rutherford backscattering spectroscopy (RBS), x-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible spectroscopy and four-point probe technique. PIXE of the precursor confirmed the presence of the expected elements that can lead to deposition of Cu-Zn-S thin film while FTIR confirmed that the organic ligands were attached to the metals. DSC showed that the precursor is thermally stable and can pyrolyze at temperature between 340°C and 460°C. RBS analysis of the films showed that there was no substantial deposition at 360°C while other films showed various stoichiometry and thickness. XRD analysis of the films showed that films deposited at 360°C and 380°C are amorphous, while those deposited between 400°C and 450°C showed peaks, in which the crystal size decreased as the deposition temperature increased. The SEM micrographs showed that the morphology of the films is temperature dependent and as deposition temperature increased larger secondary grains dissociated into smaller grains that are closely packed, without cracks and holes. Optical characterization showed that the films exhibited high transmittance, which fairly increased as the deposition temperature increased. A direct band gap value between 2.49 eV and 2.92 eV was obtained as deposition temperature increased. Urbach energy also increased from 0.87 eV to 1.51 eV, while the steepness parameter decreased as the deposition temperature increased. The electrical characterization showed that the resistivity of the films decreased as the deposition temperature increased while the I-V plot showed a rectifying character.

Hydroxyterminated polybutadiene (HTPB) based porous polyurethaneurea (PUU) membranes were prepared. The porosity was developed by incorporation of lithium chloride into polymer matrix with subsequent leaching of the same in hot water. Scanning electron microscopic analysis of the prepared membrane surfaces was performed. The pervaporation performance of the synthesized membrane was studied with aqueous 4-nitrophenol solution as feed. The effects of various parameters on 4-nitrophenol separation factor and total as well as 4-nitrophenol flux were studied. Polyurethaneurea membrane was found to permeate 4-nitrophenol selectively with high separation factors for the organic component. Pore size and number of pores on the surface of the membrane were calculated from SEM image of the membranes. Effects of pore size and porosity on pervaporation flux were also investigated.

In this paper, the ambient temperature multiferroic effect resulting from the incorporation of transition metal ions(Fe3+ andCo2+)inlead-freeBST[Ba Sr (Fe Co )Ti O ; x = 0, 0.01, 0.03, 0.05, 0.07]
0.7 0.3 x/2 x/2 1-x 3
ceramics synthesized via the solid-state reaction (SSR) procedure has been thoroughly analyzed. The
investigation consistently scrutinized the effects of augmenting transition metal co-doping on the
structural, ferroelectric, dielectric, magnetic, and magnetodielectric characteristics. The x-ray diffrac-
tion (XRD) patterns for all ceramic compositions demonstrated the formation of a monophasic (P4mm)
crystalline structure. The Raman analysis evidenced the presence of various modes, which are associated
with the occurrence of the single-phase and provide strong corroboration for the x-ray diffraction
observations. Scanning electron micrographs reveals that the inclusion of transition metal ions results in
the diminution of grain size. The frequency-dependent dielectric characteristics were represented over
the frequency range of 1 kHz to 1 MHz. The P-E hysteresis curves demonstrate a consistent reduction in
the values of Ps and Pr, whereas, the M-H curve reveals the enhancement in magnetic properties with
increased doping. The magnetodielectric analysis confirmed the interplay between the ferroelectric and
ferromagnetic ordering. The BST-1CF sample exhibited the highest MC % value of 5.30% along with
-1 -2
the magnetoelectric coupling coefficient ‘γ’ of -6.01  ́ 10 (memu/g ) , making it a favorable
entrant for the advancement of innovative non-volatile multiferroic memory gadgets.

The effect of defects in n-type GaN epitaxial layers on the electrical characteristics of Ni contacts was studied. The defect density of GaN layers was characterized, and Ni dots deposited on four n-GaN wafers with different mobilities were examined by current–voltage (I–V) and capacitance–voltage (C–V) measurements. Ni contacts deposited on undoped GaN with a mobility of 6.7 cm2/V s showed ohmic behavior with a specific contact resistance on the order of 0.1 Ω cm2. In contrast, Ni contacts deposited on Si-doped GaN with a mobility of over 100 cm2/V s exhibited Schottky behavior with a Schottky barrier height of 0.75 eV from I–V and 1.10 eV from C–V. These results suggest the formation of small areas with low barrier height at the interface due to defects and dislocations.

A1GaAs double heterostructures are grown bylow-pressure metalorganic chemical vapor deposition to evaluate the level of oxygen contamination in different trimethylaluminum sources. Effects ofarsine purifiers, misoriented substrates, atmospheric exposure of the growth chamber, and possible phosphorus contamination are also studied. Extensive characterization is performed on these films by a variety of methods, including high-resolution x-ray diffraction, photoluminescence (PL), time-resolved photoluminescence, and secondary-ion mass spectrometry. The PL intensities for structures grown with the low-alkoxide grade are reproducibly much greater than thosegrown with the regular-grade TMAl. The use of AsH~purification improves the PL intensity.

We report the characteristics of InP self-assembled quantum dots embedded in In 0.5 Al 0.5 P on GaAs substrates grown by metalorganic chemical vapor deposition. The InP quantum dots show increased average dot sizes and decreased dot densities, as the growth temperature increases from 475°C to 600°C with constant growth time. Above the growth temperature of 600°C, however, dramatically smaller and densely distributed self-assembled InP quantum dots are formed. The small InP quantum dots grown at 650°C are dislocation-free "coherent" regions with an average size of ~20 nm (height) and a density of ~1.5 × 10 8 mm -2 . These InP quantum dots have a broad range of luminescence corresponding to red or orange in the visible spectrum.