Characterization of specific contact resistance on heavily phosphorus-doped diamond films

Specific contact resistance of Ti contact on phosphorus-doped diamond film has been characterized by means of circular type transfer length method. The resistance was significantly reduced down to ～ 10^? 3 Ω cm² orders using heavily phosphorus-doped diamond film (n⁺) with phosphorus concentration over ～ 10²⁰ cm^? 3, although an ideal ohmic property was not obtained. The results are explained by a narrowing of the Schottky barrier width of Ti/n⁺ interface for tunneling through the barrier to take place, indicating that the heavily doping is promising method for reducing the contact resistance for n-type diamond.     

Challenges for energy efficiency improvement under the CDM—the case of energy-efficient lighting

The CDM under the Kyoto Protocol has so far been unable to mobilize activities of households and service industries to improve end-use energy efficiency. This is mainly due to the lack of or the cumbersome requirements of the few existing baseline and monitoring methodologies as well as the difficulty to prove project additionality. We assess methodologies for projects distributing compact fluorescent lamps to households. The approval of the first large-scale methodology took more than 2 years and in the interaction with the regulatory bodies, the methodology became very cumbersome, especially regarding monitoring requirements. Four sample groups are required and the technology that has to be used for measuring utilization of CFLs does not yet exist. Therefore, project developers are not applying the large-scale methodology but try to use the pre-defined small-scale methodology. But even the small-scale methodology requires a substantial amount of data and measurements. A “Programme of Activity” approach could reduce monitoring costs through limiting monitoring to a sample of projects. Moreover, monitoring experts could be trained and thus monitoring mistakes reduced compared to single project settings. A deemed savings methodology was recently approved which alleviates but does not completely eliminate monitoring needs. It considerably reduces CER volumes compared to the other two methodologies and thus project developers have to assess the trade-off between higher monitoring costs and lower CER volumes.     

High selectivity (SiN/SiO2) etching using an organic solution containing anhydrous HF

An etching process with high selectivity for SiN relative to SiO₂ at a low temperature is required for an etching process in LSI process. We achieved SiN film etching with high selectivity using an organic solvent (ethylene glycol dimethyl ether) containing anhydrous hydrogen fluoride. Selectivity as high as 15 was obtained at 80 °C. It was found that anhydrous HF effectively induces high selectivity for SiN relative to SiO₂. SiN film etching with high selectivity performed at low temperature for a single wafer process can be readily applied to future node technology devices.     

Urban lakes in a developing nation: Drivers,states and impacts of water quality and quantity in Dhaka,Bangladesh

This study examined pollution and shrinkage of urban lakes in the rapidly urbanizing city of Dhaka, Bangladesh. A mixed‐method approach was employed, nested within the European Environmental Agency Drivers, Pressure, States, Impacts, Responses Framework and Environmental Systems Analysis tools (as stakeholder and functions analysis methodologies). A variety of stakeholders and policymakers were first interviewed, being asked to participate in an exercise identifying their perceptions of the greatest challenges facing urban lakes in Dhaka. The current quantity and quality of lakes in Dhaka was subsequently assessed through a combination of field work, government reports and satellite imagery analysis. The results indicated that past management strategies have failed to prevent the infill and pollution of lakes and wetlands. Many key indicators of poor water quality have exhibited sharp increases over the past decade. Urban encroachment into lakes has been curtailed in only four of Dhaka’s 14 districts, with ten districts losing water land cover over the past 66 years. Policymaker and stakeholder opinions on the drivers of lake pollution were highly variable in this study, creating additional roadblocks in implementing and enforcing effective management strategies. It is concluded that the regulatory policies must be implemented to prevent furthermore environmental degradation, while also observing that such policies will be very difficult to enforce under current conditions.     

Microstructure and magnetic properties of aerosol‐deposited Sm‐Fe‐N thick films

In this study, the relationship among magnetic properties, Aerosol Deposition (AD) conditions, and microstructures in Sm‐Fe‐N AD films was investigated. The maximum thickness of 145µm was obtained under AD conditions of gas flow rate (gfr)=6liters/min for 10 min. The density of Sm‐Fe‐N films was in the range of 5.43 to 6.24g/cm³, that is, 71 to 81% of the X‐ray density of the Sm₂Fe₁₇N₃ compound reported (7.67g/cm³). The Sm‐Fe‐N AD films showed remanence in the range of 0.38 to 0.42 T, that is, 61 to 68% of that of the Sm‐Fe‐N host powder (0.62 T). The coercivities increased from 1.16 to between 1.74 and 1.79 T after the deposition because the grain size decreased from 1.94µm to 0.32µm. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 158(1): 8–13, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20214     

Electroluminescent properties of chemically synthesized zinc sulfide nanocrystals doped with manganese

High-field electroluminescence (EL) of chemically synthesized ZnS:Mn nanocrystals with a crystallite size of 4 nm was investigated using a device consisting of glass substrate/indium–tin oxide/ZnS:Mn NC emission layer/Al. For electric fields over ca. 1 MV/cm, the current was turned on, and orange EL was observed. The maximum luminance was 0.45 cd/m² at a DC voltage of 42 V. The EL spectrum comprises a single peak with a peak wavelength of 593 nm, which is ascribed to the ⁴T₁–⁶A₁ transitions of Mn²⁺ ions. The excitation mechanism of the Mn²⁺ ions is discussed according to a scheme of impact excitation by hot-electrons.     

An Assessment and Estimation of the Damage Progression Behavior of IN738LC under Various Applied Stress Conditions Based on EBSD Analysis

In order to characterize the damage progression behavior of IN738LC and the influence of applied stress, the average misorientation within grains was evaluated using the electron backscattered diffraction (EBSD) method, by measuring over a million data points located across almost the whole zone of the tested specimens. It has been shown under various test conditions such as differing temperatures and strain rates that the average misorientation increases linearly with the increase of creep strains. As a result, it is confirmed that it is possible to assess the remaining creep fracture life from its average misorientation value regardless of the testing temperature and strain rate. In addition, the deformation and fracture mechanisms of various types of mechanical damage, such as tensile, impact, and creep conditions, were discussed by evaluating the characteristics of misorientation distribution. As a result, it has been revealed that creep damage affects a large area of the material, but it is localized near grain boundaries, which is completely different from that of tensile or impact damage. In conclusion, detailed investigation into the cross section of fracture samples using the EBSD misorientation analysis allows for the qualitative estimation of the fracture mode under various applied stress conditions, the cause of the fracture.     

Evaluation of Important Factors Affecting Quench Distortion of Carburized Hypoid Gear with Shaft by Using Computer Simulation Methods

To minimize quenching distortion and dispersion, carburizing and quenching process conditions must be optimized; this includes the parts racking design used for quenching. We investigated some factors affecting carburized quenching distortion with an experiment using a hypoid gear having a shaft and with numerical simulation methods. The experimental results and those obtained from simulation were generally in agreement. Focusing on the surface temperature distribution in the gear, we studied quenching distortion characteristics in terms of changes in tooth profile and helix deviation. In our experiments, distortions occur during quenching in 373 K oil after austenitized temperature treatments conducted with various attitudes. We calculated the distortions by simulating the carburized oil-quenching process for the hypoid gear. Our results show large differences between the cooling rates of the tooth toe, middle section, and heel edges,and these greatly influence the change in tooth profile and helix deviation. We found that reducing the differences in temperatures on the gear surfaces during quenching is most important for minimizing the quench distortion of the hypoid gear.