A Practical Guide for X-Ray Diffraction Characterization of Ga(Al, In)N Alloys

Ga(In, Al)N alloys are used as an active layer or cladding layer in light emitting diodes and laser diodes. x-ray diffraction is extensively used to evaluate the crystalline quality, the chemical composition and the residual strain in Ga(Al,In)N thin films, which directly determine the emission wavelength and the device performance. Due to the minor mismatch in lattice parameters between Ga(Al, In)N alloy and a GaN virtual substrate, x-ray diffraction comes to a problem to separate the signal from Ga(Al,In)N alloy and GaN. We give a detailed comparison on different diffraction planes. In order to balance the intensity and peak separation between Ga(Al,In)N alloy and GaN, (0004) and (1015) planes make the best choice for symmetric scan and asymmetric scan, respectively.Comment: 9 pages, 5 figure

A Conceptual Framework for Motion Based Music Applications

Imaginary projections are the core of the framework for motion based music applications presented in this paper. Their design depends on the space covered by the motion tracking device, but also on the musical feature involved in the application. They can be considered a very powerful tool because they allow not only to project in the virtual environment the image of a traditional acoustic instrument, but also to express any spatially defined abstract concept. The system pipeline starts from the musical content and, through a geometrical interpretation, arrives to its projection in the physical space. Three case studies involving different motion tracking devices and different musical concepts will be analyzed. The three examined applications have been programmed and already tested by the authors. They aim respectively at musical expressive interaction (Disembodied Voices), tonal music knowledge (Harmonic Walk) and XX century music composition (Hand Composer)

Terrace grading of SiGe for high-quality virtual substrates

Silicon germanium (SiGe) virtual substrates of final germanium composition x = 0.50 have been fabricated using solid-source molecular beam epitaxy with a thickness of 2 µm. A layer structure that helps limit the size of dislocation pileups associated with the modified Frank–Read dislocation multiplication mechanism has been studied. It is shown that this structure can produce lower threading dislocation densities than conventional linearly graded virtual substrates. Cross-sectional transmission electron microscopy shows the superior quality of the dislocation network in the graded regions with a lower rms roughness shown by atomic force microscopy. X-ray diffractometry shows these layers to be highly relaxed. This method of Ge grading suggests that high-quality virtual substrates can be grown considerably thinner than with conventional grading methods

Technical pre-study for the ExMS project

This report aims to give an overview of software and hardware platforms available now or in the near future for building a prototype of an ExMS application (for an overview of the ExMS project, see Appendix). The report also gives an overview of the different technologies for building third-party mobile client software applications that are in use today. The report is composed of three sections. The first section is a general discussion on mobile client software and the different technologies that can be used to develop third-party mobile client software. The next section continues with a specific discussion on ExMS and answers the following questions: What is the general architecture of the ExMS application? What alternatives exist for implementing the ExMS prototype? The final section of the report is a recommendation of hardware and software platform for building the ExMS prototype

Towards business model and technical platform for the service oriented context-aware mobile virtual communities

The focus of existing virtual communities is centered on a particular product or social interaction and the role of mobile devices is restricted to exchange a limited amount of contents. Herewith we envisage that the upcoming virtual communities will exploit the potential of social interaction and context information to offer personalized services to its members and mobile devices will play a significant role in this process. As a step towards this direction, in this paper we propose a business model for the mobile virtual communities in which the mobile device takes on the role of a content producer and content consumer. Though there are a number of research issues which need to be addressed to realize such virtual communities, in this paper we focus on the service requirements, architecture and open source software implementation of a technical platform for the content producer and consumer mobile devices