is tentative since no eutectic but a eutectoid temperature is available and used. Another trend observed in the plot is that barrier heights of silicides of the same metal such as PtSi and Pt 2 Si do not vary very much. The important meaning of this trend is unclear yet and requires further studies.The most significant information revealed in the above figures is that there is a correlation between Schottky-barrier heights and eutectic temperatures. Although we cannot yet explain this correlation from the first principle, its physical meaning seems to be understandable starting from the Si-to-Si contact; as the interfacial layer becomes metallic, its melting point decreases while its barrier height increases. Finally, we speculate that the same interfacial layer dependence will also play a role on other covalent semiconductors such as GaAs.The authors would like to thank J. C. McGroddy for a review of the paper. (a) Permanent address: Institute of Physics, Modena,The carrier-recombination properties of dislocations in semiconductors and their effects on devices are now well-established facts. To account for such properties, Read 1 and later Hornstra 2 have proposed a dangling-bond model for the core of the clean dislocation. Recent studies of the dislocation electronic properties with use of EPR, 3 deep-level transient spectroscopy (DLTS), 4 ' 5 and Hall-conductivity measurements 6 indicate that the density of electrically active sites along a clean dislocation core is indeed much smaller than the number of atomic sites Italy. 1 E. H. Rhoderick, Metal Semiconductor Contacts (Clarendon, Oxford, 1978).
SUMMARY Carrier recombination at individual dislocations is investigated for the case of misfit dislocations at a heterojunction between Ga1–xAlxAs1–yPy epitaxial layers. Through the combined use of scanning transmission electron microscopy, electron beam induced current and cathodoluminescence analysis, it is shown that the non‐radiative and radiative recombination properties of dislocations are associated with their fine crystallographic configuration. The edge Lomer‐Cottrell dislocation is found to be electrically neutral. The absence of carrier recombination strongly suggests that core reconstruction may be important in eliminating dangling bonds and kink sites along the core of these dislocations. An undissociated dislocation with a Burgers vector b=1/2a〈110〉 is proposed as the more likely configuration for the edge Lomer‐Cottrell dislocation. An asymmetry in the nonradiative recombination properties and crystallographic structure of the 60° dislocation is also reported and discussed.
This paper looks at how BT and Hewlett Packard (HP) were able to use the BT HP alliance to address a key customer hosting requirement, as part of a major outsourcing opportunity in the finance sector. It shows how the two organisations collaborated to develop the solution and outlines the way the bid was put together. The paper illustrates how the strengths of both organisations contributed to developing a sound proposition and describes the service model and technologies which make up the solution. This is achieved by looking at the commercial context of the bid and the technical solution. The transfer of the service to HP's premises, using their TTM methodology is considered, as is the ongoing support through the joint BT and HP service model. Finally the lessons learned from the bid are examined. IntroductionTowards the end of 2005, a major financial institution looked to the IT services market to outsource its principal communications services, including the hosting of its Internet banking and mortgage processing capabilities. In order to respond to this requirement, the BT HP alliance looked at how best to leverage the strengths of both organisations to provide an industry leading service for this part of the customer's requirement.The service was to be migrated from the existing outsource service providers to HP's facilities at Reading and Newbury using HP's transition and transformation methodology (TTM) [1]. The TTM process begins with a planning phase, followed by the transfer of the existing facility into the HP data centres at Reading and Newbury.Once HP and BT had run the service for a while, a design activity would take place to look at ways of making the installation more efficient, scalable and cost effective, using the principles embodied in the integrated services architecture (ISA) [2].The terms used in TTM do not precisely overlap with the standard terms used in ICT outsourcing programmes, but this was addressed by modifying the nomenclature in line with accepted practice, and by BT managing the phase prior to the servers transferring to HP premises. This activity, which covers the negotiations with the existing vendors and the novation of relevant contracts, is traditionally known as transition.The wider contract also covered management by BT of the customer's firewall estate, resulting in a transformed two-layer firewall service, based on both stateful and application proxy server technology. This was to be introduced into the HP environment as part of the configuration of the migrated service. In addition, BT were to provide the Internet connectivity and all LAN and WAN communications, with HP taking responsibility for Web hosting and load balancing. These services were to be implemented using BT and HP's combined IT service management framework and fronted by a contract-wide service desk provided by BT. Overall management of the computing platforms was to be maintained using the HP OrbIT tool-set.A number of implementation challenges were anticipated:• maintaining service during the move f...
Letter from. .. Africa Do-it-yourself medicine ANNE SAVAGE The uncertainties in this investigation began at the beginning, for no one ever knew the name, or even the age, of the little girl who became the index case. She was admitted unconscious with no history and a couple of days later she died, but before she did a distended, tympanitic, silent abdomen gave the clue,
A method is described whereby the comparative areas of irregularly shaped microscopic objects may be rapidly determined. It consists of staining them with fuchsine and projecting their magnified images into a photo-electric cell insensitive to red light. The photo-electric current is inversely proportional to the sizes of the images and, at low magnifications, may be measured with a sensitive galvanometer.
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