Source Meter Research Articles

White Electroluminescence from a Gadolinium-Doped Si-Nanocluster-Enriched SiO[sub 2]–SiON Interface Region

SiO2 implanted with carbon and silicon. In this article, we present bright white light emitters based on the silicon-rich SiO2‐SiON interface in a metal‐SiON‐SiO2‐Si MONOS structure coimplanted with gadolinium Gd. At a certain level of the constant injection current excitation, the MONOS structure containing Si-nc and Gd works as a white light emitter. At a constant current excitation of 100 A, the EL spectrum covers a wide spectral region from 360 to 700 nm with a broad flat region of about 200 nm. The increase in the constant current excitation switches the color of the light emitters observed by the naked eye from green to blue. For constant current excitation above 1 mA, the energy transfer from the Gd 3+ ions to the neutral oxygen vacancy defects and the silicon nanoclusters was observed. The photoluminescence PL measurements taken from only silicon implanted structures show two broad-bands with peaks at 640 and 780 nm. In Gd coimplanted Si-rich MONOS structures, the PL spectrum consists of one peak at 650 nm related to a nonbridging oxygen hole center NBOHC and two peaks at 760 and 830 nm associated with silicon nanoclusters with sizes of 1.7 and 1.8 nm, respectively. EL devices, metal‐SiON‐SiO2‐Si light emitting device MONOSLED, were prepared by a standard silicon MOS technology on 4 inch, n-type silicon 100 wafers with resistivities of 2‐5 cm. Thermally grown 100 nm thick SiO2 layers with a 1000 nm field oxide were processed using the local oxidation of silicon technology and were implanted by silicon and coimplanted with Gd at energies of 20 and 140 keV with atomic concentrations of 10 and 2%, respectively. Samples were annealed at 1100°C for 30 min after silicon implantation to form Si-nc and at 900°C for the same time after Gd coimplantation to reduce the radiation defects and to rebuild Si-nc. To protect the oxide layer against breakdown, a 200 nm SiON layer was deposited on top of it O:N =1 :1 by plasmaenhanced chemical vapor deposition. The atomic composition of the SiON layers and the concentration of implanted elements were confirmed by scanning Auger electron spectroscopy Microlab 310F. The gate and bottom electrodes consist of a 100 nm thick indium tin oxide ITO layer deposited by radio frequency sputtering and a 300 nm thick evaporated Al layer, respectively. Cross-sectional transmission electron microscopy images were taken by means of an FEI Titan 80-300 scanning transmission electron microscope operating at 300 keV. The EL measurements were performed using electron injection mainly from the ITO electrode. The EL spectra and the quenching of the EL intensity were measured at room temperature on MONOS structures with a circular ITO electrode of 300 m diameter at a constant current supplied by a source meter Keithley 2410. The EL signal was recorded with a monochromator Jobin Yvon Triax 320 and a photomultiplier Hamamatsu H7732-10 .P L experiments were conducted at room temperature with an excitation wavelength of 514.5 nm from an argon laser with a power density of 0.2 mW/mm 2 . The PL signal was recorded with an SPM-2 monochromator and a photomultiplier Hamamatsu R943-02. The photograph was taken by a standard digital camera combined with a microscope. Figure 1 shows the PL spectra taken from Si-nc’s embedded in the SiO2 layer and from the SiO2 layer containing Si-nc’s coimplanted with Gd. In the silicon implanted oxide layer with subsequent annealing at 1100°C, the PL signal shows a broad spectrum with two main bands centered at around 650 and 800 nm. The Gaussian peak deconvolution inset of Fig. 1 enables us to show

Resistivity dependent dielectric and magnetic properties of Pb(Fe0.012Ti0.988)O3 nanoparticles

High resistivity in nanostructured Pb(Fe0.012Ti0.988)O3 system prepared by using polyvinyl alcohol (PVA) in chemical route is observed. The PVA acts as a surfactant to limit the particle size. The Fe substitution for Ti controls the chemical stoichiometry and reduces the lattice distortion, i.e., c/a ratio, and hence the transition temperature reduces with Fe content. The phase structure, morphology, particle size, dc resistivity, and dielectric and magnetic properties of Pb(Fe0.012Ti0.988)O3 nanoparticles have been characterized by x-ray diffraction, transmission/scanning electron microscopy, source meter, LCR meter, and vibrating sample magnetometer. The results indicate that the nanosize particles have high resistivity, which improves the dielectric constant at high-frequency region and increases magnetization of the specimens. The observed variable-range-hopping conduction mechanism indicates that Fe doping leads to the occurrence of local defect states in the PbTiO3 lattice. The dispersionless dielectric properties with low loss are observed up to 15 MHz. The dielectric properties are improved than those obtained by the conventional process. The initial permeability values do not exhibit much variation up to ferromagnetic transition temperature after which it falls sharply. The large value of saturation magnetization is observed at room temperature.

Optical parameters of nanostructured thin films of electromagnetite Pb1−x Sr x (Fe0.012Ti0.988)O3

Polycrystalline Pb1−xSrx(Fe0.012Ti0.988)O3 (0.2≤x≤0.4) (PSFT) thin films have been grown on fused quartz substrates by metallo-organic decomposition technique. The grown films were characterized using X-ray diffraction (XRD), atomic force microscopy (AFM), source meter and UV–Vis–NIR spectrophotometer to determine the structural, microstructural, dc resistivity and optical properties. The XRD pattern confirmed that the PSFT films has distorted tetragonal single phase, which close to cubic at higher Sr concentration. AFM analysis revealed that the grains size reduces with increasing Sr concentration and their average values lies in the range of 26–9 nm. The higher values of dc resistivity of PSFT nano grains indicate that the transmission of light occurs within these grains up to short wavelength. The refractive index and the extinction coefficient were determined from the optical transmission spectrum in the wavelength range of 200–1100 nm and compared with that theoretically calculated, when fitted to a single oscillator model. The values of optical band gap were determined from Tauc’s extrapolation fitting and suggests that the transformation of electrons during transmission of light through local states within Fermi gap.

Effect of Erbium Dopant on Conductivity of Antimony‐Doped Tin Oxide (ATO) Nanoparticles

ATO nanoparticles doped with erbium were prepared using chemical co‐precipitation method. Meanwhile, the conductivity of nanoparticles was investigated using Source Meter. The results indicate that erbium dopant has great effect on the electrical property of the ATO nanoparticles. Compared with undoped ATO nanoparticles, the resistivity of ATO nanoparticles doped with 0.5 mol% erbium decreased by a factor of 800. This may be ascribed to formation of acceptor lever near valence band of ATO due to the presence of f energy lever of rare earth element. The effect of annealing temperature on the electrical property of the erbium‐doped ATO nanoparticles was also explored.

Electrical Property of Tin Oxide Doped with Multi‐Walled Carbon Nanotubes

Tin oxide doped with multi‐walled carbon nanotubes (MWNTs) was prepared via a wet‐chemical process and characterized with x‐ray diffraction (XRD) and transmission electron microscope (TEM). Meanwhile, the conductivity of composites obtained was measured using Source Meter. The results show that carbon nanotubes have great effect on the electrical property of SnO2 nanoparticles. Compared with undoped SnO2 nanoparticles, the resistivity of SnO2 nanoparticles doped with 0.3‰ wt MWNTs decreased by a factor of 37. This may be ascribed to the presence of π energy levers of MWNTs and their high aspect ratio. Moreover, the effect of annealing temperature on the electrical property of SnO2 nanoparticles doped with MWNTs also was discussed.

패턴된 전극을 가진 표면 전도형 단실형 고체산화물 연료전지의 제조

Co-planar type single chamber solid oxide fuel cell with patterned electrode on a surface of electrolyte has been fabricated by robodispensing method and microfluidic lithography. The cells were composed of NiO-GDC-Pd or NiO-SDC cermet anode, (La 0.7 Sr 0.3 ) 0.95 MnO₃ cathode, and yttria stablized zirconia electrolyte. The cell performance at 900℃ was investigated as a function of electrode geometries, such as anode-to-cathode distance, numbers of electrode pairs. Relationship between OCV and I-V characteristics at the optimized operation condition was also studied by DC source meter under the mixed gas condition of methane, air, and nitrogen. An increase of anode-facing-cathode area leads to lower OCV due to intermixing between product gases of anode and cathode, which in turn decreases the oxygen partial pressure difference.

Co-planar type single chamber solid oxide fuel cell with micro-patterned electrodes

A co-planar type single chamber solid oxide fuel cell (SC-SOFC) with linearly patterned electrode structures on the same surface as the electrolyte has been fabricated by robo-dispensing method. Paste materials of NiO-SDC-Pd cermet and (La0.7Sr0.3)0.95MnO3 (LSM) were selectively deposited onto a substrate of yttria stablized zirconia (YSZ) by extrusion through a syringe nozzle. The dispensed pastes were solidified upon solvent evaporation, and the anode and the cathode were sintered at 1350∘C for 2 h and 1200∘C for 1h, respectively. We have fabricated SC-SOFCs that have a single electrode pair with varying anode-to-cathode distances and interdigitated patterned electrodes with 2, 4, and 8 multiple pairs. The electrode microstructures of the resulting cells were examined by SEM. The electrochemical performance of the SC-SOFCs was also analyzed using impedance spectroscopy and a DC source meter.

Characteristics of the polyaniline films vacuum deposited at a high background pressure

Polyaniline films with different thickness were deposited on unheated glass substrates by vacuum evaporating HCl-doped polyaniline pellets at a high background pressure. Micromorphological, compositional, structural and electrical properties of the films were studied by using field emission scanning electron microscopy, energy dispersive of X-ray spectroscopy, Fourier transform infrared spectroscope and sub-femtoamp source meter. The polyaniline films consist of a large number of flakes. Some flakes are perpendicular to the substrate and they are more in the thick film compared with the thin film. No chlorine is detected in the films. The aromatic structure of polyaniline is retained in all the polyaniline films. However, the polar structure of polyaniline is destroyed in the films. The polyaniline film is in a higher oxidation state compared with the HCl-doped polyaniline pellet. The conductivity of the polyaniline films ranges from 10 −8 to 10 −9 S/cm and is lower than that of the HCl-doped polyaniline pellet as the starting material. Besides, the conductivity decreases with increasing film thickness.

초소형 광정보저장기기용 웨이퍼 스케일 대물렌즈 제작을 위한 회절광학소자 성형기술 개발

The demand fer small and high-capacity optical data storage devices has rapidly increased. The areal density of optical disk is increased by using higher numerical aperture objective lens and shorter wavelength source. A wafer-scale stacked micro objective lens with a numerical aperture of 0.85 and a focal length of 0.467mm for the 405nm blue- violet laser was designed and fabricated. A diffractive optical element (DOE) was used to compensate the spherical aberration of the objective lens. Among the various fabrication methods for micro DOE, the UV-replication process is more suitable fur mass-production. In this study, an 8-stepped DOE pattern as a master was fabricated by photolithography and reactive ion etching process. A flexible mold was fabricated for improving the releasing properties and shape accuracy in UV-replication process. In the replication process, the effects of exposing time and applied pressure on the replication quality were analyzed. Finally, the surface profiles of master, mold and molded pattern were measured by optical scanning profiler. The geometrical deviation between the master and the molded DOE was less than <TEX>$0.1{\mu}m$</TEX>. The diffraction efficiency of the molded DOE was measured by DOE efficiency measurement system which consists of laser source, sample holder, aperture and optical power meter, and the measured value was <TEX>$84.5\%$</TEX>.

Single-Chamber Solid Oxide Fuel Cell with Micropatterned Interdigitated Electrodes

A single-chamber solid oxide fuel cell (SC-SOFC) with micropatterned electrodes on the electrolyte has been fabricated by a microfluidic lithography technique. Microchannels formed by contacting the polydimethylsiloxane mold with a polished substrate of YSZ disk were filled with the well-dispersed suspensions of the cathode and the anode. The suspensions solidified upon solvent evaporation through the mold, resulting in the SC-SOFC with interdigitated micropatterned electrodes in an area of 5 X 5 mm in which each electrode had 100 μm line width with anode-to-cathode distances of 50 μm. I-V characteristics of the SC-SOFC were analyzed using a dc source meter.

Single-Chamber Solid Oxide Fuel Cell with Micro-Patterned Interdigitated Electrodes

Single-chamber solid oxide fuel cells (SC-SOFCs) with micropatterned electrodes on the electrolyte have been fabricated by microfluidic lithography. Microchannels formed by contacting the PDMS mold with a polished substrate of YSZ disc were filled with the suspension of NiO-SDC cermet anode by vacuum-assisted infiltration followed by solidification upon solvent evaporation through the mold. After sintering the anode at 1300°C for 2 hr, the PDMS mold was aligned and recontacted with an anode-patterned electrolyte. The LSM cathode material was patterned and sintered at 1200°C for 2 hr in the same manner as anode fabrication. The resulting SC-SOFC has micro-patterned interdigitated electrodes in a 5 x 5 mm 2 area in which each electrode had 100 μm line width and anode-to-cathode distance of 50 pm. The microstructure of the cell was examined by SEM. I-V characteristics were analyzed using a DC source meter.

Digital system for vacuum and gas-filled devices testing

This article describes an improved electrical system aimed at measuring and data acquisition of the breakdown voltage of vacuum and gas-filled devices at low pressures using a discretized dynamic method. The previous system [M. M. Pejovic, C. S. Milosavljevic, and M. M. Pejovic, Rev. Sci. Instrum. 74, 3127 (2002)] included a complex analog circuit for breakdown detection, which did not provide the required reliability. The smallest voltage step which this system could provide was 250 mV. In order to increase the reliability of the breakdown detection, the Keithley model 248 high power supply was added to the system. The breakdown is detected from a monitor output at model 248 rear panel. The disadvantage of this system was the fact that the minimal value of the voltage step in this case is 1 V. An additional Keithley model 2400 Source Meter was introduced as a serial connection with the Keithley model 248 with the aim of decreasing the minimal value of the voltage step, which is in this case 1 mV. PC controls both Keithley models using standard IEEE 488 interface bus. This system provides a minimal voltage step value of 1 mV which results in a high precision in breakdown voltage determination. The proposed system controls a large number of parameters, which makes significantly influences the breakdown voltage value. The system was tested with a neon-filled tube at 6.6 mbar, where two parameters were varied, the relaxation time and the voltage step. The experimental results are in accordance with the literature regarding the influence of these two parameters on the breakdown voltage of gas-filled tubes.

High power spectrometer for the characterization of photovoltaic cells in a controlled atmosphere or vacuum

The complete description of a high power spectrometer, allowing for large area illumination of up to 10 cm2 in the wavelength range 200–800 nm with average power densities of 2 mW cm2, is provided. The setup employs a stationary 150 W xenon lamp used in conjunction with a simple stationary single monochromator grating. The photovoltaic sample under test is placed in a stainless-steel vacuum chamber allowing for operating pressures down to 10−6 mbar equipped with a quartz window and electrical connections. The entire vacuum chamber was placed on a moving arm allowing for positioning in a selected part of the diffracted beam of the monochromator. The typical spectral resolution was 12 nm cm−1 which gave bandwidths of 25 nm with a 2 cm sample width. The electrical characteristics of the photovoltaic device under test was measured using a source meter giving an experimental current sensitivity of 10 pA. We finally demonstrate the application of the instrumental setup for the characterization of a polymer based photovoltaic.

Measurement of the sheet resistance of resistive films on thin substrates from 120 to 175 GHz using dielectric waveguides

A method is reported for the measurement of the sheet resistance, at microwave frequencies, of conducting films supported on thin dielectric substrates. The sheet resistance is found from measurements of the millimeter-wave power transmission through the film using a millimeter-wave source and power meter coupled through dielectric waveguides. The accuracy of this technique does not depend on the precise placement of the waveguide terminations with respect to the substrate, in contrast to methods using metallic waveguides or coils. This method is used to characterize the sheet resistance of semiconductor samples in the frequency range 120–175 GHz and the results are compared to the dc values obtained by conventional techniques. Sheet resistance values can be easily measured by this method in the range from 1 to 1000 Ω.

Responsiveness of flocculus and paraflocculus purkinje neurons to step-ramp like smooth pursuit eye movements

Multifunctional nano composite coatings of Zn-TiO2-WO3 were deposited electrolytically on mild steel (MS) from Zn bath, having Zn2+ ions and uniform dispersion of TiO2 and WO3 nano particulates. The electrical, optical and corrosion resistance characteristics of the electrocodeposited coatings were assessed by Keithley 2400 Series Source meter with Multimeters, Newport Solar Simulator and a PGSTAT30 Autolab potentiostat respectively. The morphological characteristics of the composite coatings were characterized by scanning electron microscope (SEM) equipped with energy dispersive spectrometer (EDS). The result revealed that the electrocodeposits showed good stability and Zn-TiO2-WO3 nanocomposite deposits displayed enhanced microstructural qualities, good electrical conductivity and exhibited enriched corrosion resistance.

Meter Installation Saves Money for District

Installation of four new source meters and the repair of an old source meter resulted in financial and operational benefits for Trentwood Irrigation District No. 3 in Washington State. Repair of the broken meter showed that its pump was not delivering water and had not been for many years. Installation of four source meters led to the discovery that the district's total daily water demand during the fall could be supplied by one pump. The combination of the money saved and charging for water on a cost‐of‐service basis allows the district to be financially successful.

A comparison of the noise environment in open‐plan and traditional single family dwellings

The noise environment within two single family dwellings was investigated using a sound power source and sound level meter. The dwellings have three levels and are roughly the same size. One of the dwellings is an open‐plan design, both within and between levels, and the other is a traditional multilevel design. Both dwellings are representative of common residential construction and neither incorporate special noise control features. Octave band pressure levels from 125 Hz to 8 kHz were measured at eight locations in each dwelling for each of three source locations. Average NC values in living areas of the traditional dwelling were found to be 7 dB less than in the open‐plan dwelling. In bedroom areas, the average NC values were more than 20 dB lower in the conventional dwelling. These results are in good agreement with those of a previous study [D. K. Holger and M. S. Pickett, J. Acoust. Soc. Am. Suppl. 1 72, S91 (1982)] which concluded that boundary absorption is very important in open‐plan residential design. [Work supported by the Engineering Research Institute.]

An Automatic Network Analyzer Using a Slotted Line Reflectometer

An automatic network analyzer (ANA) based on a 5-port reflectometer is presented. The measuring circuit consists of a slotted waveguide with sliding probe. A group of three fixed probes may be used instead. A microwave source, frequency counter, and power meter are used all controlled by a desktop computer. The theory is simple and the algorithm for obtaining the complex reflection coefficient from experimental data is fast. Some results are given for measurements earned out at X-band frequencies. Successful measurement accuracy is achieved with relatively noncomplex hardware. Multioctave bandwidth operation is expected for the proposed technique.