J. Appl. Cryst.の発刊に際して

This paper gives the 2010 self-consistent set of values of the basic constants and conversion factors of physics and chemistry recommended by the Committee on Data for Science and Technology (CODATA) for international use. The 2010 adjustment takes into account the data considered in the 2006 adjustment as well as the data that became available from 1 January 2007, after the closing date of that adjustment, until 31 December 2010, the closing date of the new adjustment. Further, it describes in detail the adjustment of the values of the constants, including the selection of the final set of input data based on the results of least-squares analyses. The 2010 set replaces the previously recommended 2006 CODATA set and may also be found on the World Wide Web at physics.nist.gov/constants.

/pdf/codata-recommended-values-of-the-fundamental-physical-4bsdant71c.pdf

CODATA Recommended Values of the Fundamental Physical Constants: 2006

Fuel cells are uniquely capable of overcoming combustion efficiency limitations (e.g., the Carnot cycle). However, the linking of fuel cells (an energy conversion device) and hydrogen (an energy carrier) has emphasized investment in proton-exchange membrane fuel cells as part of a larger hydrogen economy and thus relegated fuel cells to a future technology. In contrast, solid oxide fuel cells are capable of operating on conventional fuels (as well as hydrogen) today. The main issue for solid oxide fuel cells is high operating temperature (about 800°C) and the resulting materials and cost limitations and operating complexities (e.g., thermal cycling). Recent solid oxide fuel cells results have demonstrated extremely high power densities of about 2 watts per square centimeter at 650°C along with flexible fueling, thus enabling higher efficiency within the current fuel infrastructure. Newly developed, high-conductivity electrolytes and nanostructured electrode designs provide a path for further performance improvement at much lower temperatures, down to ~350°C, thus providing opportunity to transform the way we convert and store energy.

http://science.sciencemag.org/content/sci/334/6058/935.full.pdf

Lowering the Temperature of Solid Oxide Fuel Cells

Review on recent progress of nanostructured anode materials for Li-ion batteries

The role of extended and point defects, and key impurities such as C, O, and H, on the electrical and optical properties of GaN is reviewed. Recent progress in the development of high reliability contacts, thermal processing, dry and wet etching techniques, implantation doping and isolation, and gate insulator technology is detailed. Finally, the performance of GaN-based electronic and photonic devices such as field effect transistors, UV detectors, laser diodes, and light-emitting diodes is covered, along with the influence of process-induced or grown-in defects and impurities on the device physics.

Gan : processing, defects, and devices

One alternative to conventional rapid thermal annealing (RTA) of implants for ultra-shallow junction formation is that of laser annealing. Laser thermal processing (LTP) incorporates an excimer pulsed laser capable of melting the near surface region of the silicon (Si) substrate. The melt depth is dependent upon the energy density supplied by the irradiation source and the melting temperature of the substrate surface. A process window associated with this technique is able to produce similar junction depths over a range of energy densities due to the melting temperature depression established with pre-amorphization of the substrate surface prior to dopant incorporation. The process window of germanium (Ge) preamorphized, boron (B) doped Si was investigated. 200 mm (100) n-type Si wafers were preamorphized via 18 keV Ge + implantation to 1x10 15 /cm 2 and subsequently implanted with 1 keV B + to doses of 1x10 15 /cm 2 , 3x10 15 /cm 2 , 6x10 15 /cm 2 , and 9x10 15 /cm 2 . The wafers were laser annealed from 0.50 J/cm 2 to 0.88 J/cm 2 using a 308 nm XeCl excimer irradiation source. Transmission electron microscopy (TEM) was used to determine the process window for each implant condition, and correlations between process window translation and impurity concentration were made. Four-point probe quantified dopant activation and subsequent deactivation upon post-LTP furnace annealing.

Electrical and Structural Characterization of Boron Implanted Silicon Following Laser Thermal Processing

We have characterized MOCVD grown ZnS layers for thin film electroluminescence (TFEL) devices. Films with thicknesses ranged from several A to 2 μm were studied by x-ray diffractometry (XRD), cross-sectional transmission electron microscopy (XTEM), high-resolution transmission electron microscopy (HRTEM), and ultraviolet-visible photospectrometry (UVS). From HRTEM micrographs, it was observed that ZnS films consist of a mixture of hexagonal and cubic phases. Correlation of UV absorption spectra with XRD analysis resulted in a method for quantitative determination of the cubic packing fraction of polymorphic ZnS films. The initial ZnS layer (< 1000 A) deposited on BaTa2O6 had more hexagonal than cubic phase because of denser crystal defects. However, the fraction of cubic phase increased with the film thickness. In addition to film microstructures, the mean grain size, growth rate, film uniformity, and surface roughness of MOCVD grown ZnS thin films as functions of film thicknesses and substrate temperatures were also calibrated by XTEM results.

Characterization of ZnS Layers Grown by MOCVD for Thin Film Electroluminescence (TFEL) Devices

We have investigated the feasibility of depositing GaN, AIN and InN from nitrogen plasmas by electron cyclotron resonance-metal organic molecular beam epitaxy (ECR-MOMBE). Growth rate, morphology, and resistivity were evaluated as function of growth temperature and group IB flux. It was found that stoichiometric materials could be deposited at reasonable growth rates on either GaAs or sapphire substrates. Low contact resistance, ∼5 × 10−7 Ω-cm2, can be obtained on In due to the high carrier concentrations, 1020 cm−3 obtained in this material.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S1946427400445896

Growth of GaN, AlN and InN by Electron Cyclotron Resonance-Metal Organic Molecular Beam Epitaxy

Cross-sectional transmission electron microscopy (TEM) sample preparation of ZnSeiGaAs epitaxial films is investigated. Conventional argon ion milling is shown to produce a high density (-5-8 x 101'icm2) of small (diameter -60-80 A) extended defects (stacking faults, microtwins, double positioning twins, etc.?. In addition, transmission electron diffraction results indicate a thin ZnO layer can also occasionally form upon ion milling or electron-beam irradiation although the exact conditions for ZnO formation are not well understood. Conventional TEM (amplitude contrast) and high-resolution TEM (phase contrast) imaging in combination with trans- mission electron diffraction studies were performed to determine the optimum method of removing the ion milling related damage and ZnO layers during sample preparation. HFiHCl, NaOH/H,O, H2S0,1H202/H,0 and Br,/CH,OH etching mixtures as well as low voltage argon or iodine ion milling were studied. A low energy (2 keV) iodine or argon ion milling step was shown to remove the ZnO layer and reduced the density of the extended defects associated with Ar + ion milling, but was unsuccessful in removing all of the defects. Auger electron spectroscopy results indicate re- sidual iodine was either left on the surface or implanted beneath the surface during iodine ion milling. Etching the XTEM samples in HFiHCl was shown to be effective in removing the ZnO layer but had little or no effect on the ion milling induced defects. Etching the samples in a 0.5% Br,iCH,OH solution resulted in complete elimination of the ion milling induced extended defects including the residual defects associated with iodine ion milling. In addition the Br,iCH,OH etch produced the best surface morphology. Thus a brief (1-2 seconds) Br,/CH,OH etch after conven- tional preparation (argon ion milling) of cross-sectional ZnSeiGaAs TEM samples appears to be an inexpensive and superior alternative to iodine ion milling. Sample preparation, ZnO formation, Ion milling

A Technique for the Preparation of Cross-Sectional TEM Samples of ZnSe/GaAs Heterostructures Which Eliminates Process-Induced Defects

An attempt was made to deposit a high thermally stable silicon dioxide (SiO2) film onto InP substrates. The films were grown by rapid thermal, low‐pressure chemical vapor deposition (RT‐LPCVD), using pure oxygen (O2) and 2% diluted silane (SiH4) in argon (Ar) gas sources, in the temperature range of 350–550 °C and pressure range of 3–10 Torr. The SiO2/InP structures were heated, post‐deposition, up to 1000 °C for durations of up to 5 min, resulting in negligible changes in the properties of the SiO2 films and a limited SiO2/InP interfacial reaction of about 15 nm thick. The higher the initial deposition temperature of the SiO2 the larger was the film compressive stress and the less the degree of densification the film underwent through the post‐deposition heating cycles.

Kevin S. Jones

Papers

Electrical and Structural Characterization of Boron Implanted Silicon Following Laser Thermal Processing

Characterization of ZnS Layers Grown by MOCVD for Thin Film Electroluminescence (TFEL) Devices

Growth of GaN, AlN and InN by Electron Cyclotron Resonance-Metal Organic Molecular Beam Epitaxy

A Technique for the Preparation of Cross-Sectional TEM Samples of ZnSe/GaAs Heterostructures Which Eliminates Process-Induced Defects

Highly stable silicon dioxide films deposited by means of rapid thermal low‐pressure chemical vapor deposition onto InP