Rapid thermal annealing processing of GaN epilayer on sapphire(0 0 0 1)

The effect of rapid thermal annealing (RTA) in a Nz ambient up to 900 degrees C has been investigated for GaN films grown on sapphire(0 0 0 1) substrates. Raman spectra, X-ray diffractometry and Hall-effect studies were performed for this purpose. The Raman spectra show the presence of the E-2 (high) mode and a shift in the wave number of this mode with respect to the annealing processing. This result suggests the presence and relaxation of residual stress due to thermal expansion misfit in the films which are confirmed by X-ray measurements and the structure quality of GaN epilayer was improved. Furthermore, the electron mobility increased at room temperature with respect to decrease of background electron concentration after RTA. (C) 1998 Elsevier Science B.V. All rights reserved.

Processing network models of energy/environment systems

Processing networks are a variant of the standard linear programming network model which are especially useful for optimizing industrial energy/environment systems. Modelling advantages include an intuitive diagrammatic representation and the ability to incorporate all forms of energy and pollutants in a single integrated linear network model. Added advantages include increased speed of solution and algorithms supporting formulation. The paper explores their use in modelling the energy and pollution control systems in large industrial plants. The pollution control options in an ethylene production plant are analyzed as an example. PROFLOW, a computer tool for the formulation, analysis, and solution of processing network models, is introduced.

yet another meta-language for programming language processing

The formal specification language LFC was designed to support formal specification acquisition. However, it is yet suited to be used as a meta-language for specifying programming language processing. This paper introduces LFC as a meta-language, and compares it with ASF+SDF, an algebraic specification formalism that can also be used to programming languages.

Optical image processing using the photoinduced anisotropy of pyrrylfulgide

A synthesized photochromic compound-pyrrylfulgide-is prepared as a thin film doped in a polymethylmethacrylate (PMMA) matrix. Under irradiation by UV light, the film converts from the bleached state into a colored state that has a maximum absorption at 635 nm and is thermally stable at room temperature. When the colored state is irradiated by a linearly polarized 650 nm laser, the film returns to the bleached state; photoinduced anisotropy is produced during this process. Application of optical image processing methods using the photoinduced anisotropy of the pyrrylfulgide/PMMA film is described. Examples in non-Fourier optical image processing, such as contrast reversal and image subtraction and summation, as well as in Fourier optical image processing, such as low-pass filtering and edge enhancement, are presented. (c) 2006 Optical Society of America.

A new method for spectrum reproduction and interferogram processing

On the basis of researchon the theory and mathe matics of interference data collection of the spatially modulated polarization interference imaging spectrometer designed by us, this paper mainly analyses and compares three different methods of spectrum reconstruction and interferogram processing. Specially, the authors introduce the nonparametric model of Music algorithm which is maturely used in power spectrum estimation into the spectrum reconstruction processing for the first time. This method prodigiously improves the resolution of reproduced spectrum, and provides a better math matic model for the improvement of resolving power in spectrum reproduction.

Real-time data processing of interferential imaging spectrometer based on FPGA

Based on the data processing technologies of interferential spectrometer, a sort of real-time data processing system on chip of interferential imaging spectrometer was studied based on large capacitance and high speed field programmable gate array( FPGA) device. The system integrates both interferograrn sampling and spectrum rebuilding on a single chip of FPGA and makes them being accomplished in real-time with advantages such as small cubage, fast speed and high reliability. It establishes a good technical foundation in the applications of imaging spectrometer on target detection and recognition in real-time.

Liquid encapsulated-melt zone processing of GaAs

A liquid encapsulated melt Bone process has been developed for single crystal growth of GaAs. Single crystals of 40 mm long have been grown with this technique. To avoid unwanted nucleation events and maintain a constant crystal diameter, from top to bottom growth using a short zone with a convex zone surface was found to give the best results. An arsenic overpressure was used to in conjunction with a B2O3 encapsulant in order to suppress arsenic dissociation from the melt and maintain the stoichiometry of the crystal.

Structural properties of polycrystalline silicon films formed by pulsed rapid thermal processing

A novel pulsed rapid thermal processing (PRTP) method has been used for realizing the solid-phase crystallization of amorphous silicon films prepared by PECVD. The microstructure and surface morphology of the crystallized films are investigated by X-ray diffraction (XRD) and atomic force microscopy (AFM). The results indicate that this PRTP is a suitable post-crystallization technique for fabricating large-area polycrystalline silicon films with good structural qualities such as large grain size, small lattice microstain and smooth surface morphology on low-cost substrate.

JFET SOS devices: Processing and gamma radiation effects

A process for fabricating n channel JFET/SOS (junction field-effect transistors on silicon-on-sapphire) has been researched. The gate p(+)n junction was obtained by diffusion, and the conductive channel was gotten by a double ion implantation. Both enhancement and depletion mode transistors were fabricated in different processing conditions. From the results of the Co-50 gamma ray irradiation experimental we found that the devices had a good total dose radiation-hardness. When the tot;ll dose was 5Mrad(Si), their threshold voltages shift was less than 0.1V. The variation of transconductance and the channel leakage current were also little.

Improved digital processing method used for image motion measurement based on hybrid opto-digital joint transform correlator

Hybrid opto-digital joint transform correlator (HODJTC) is effective for image motion measurement, but it is different from the traditional joint transform correlator because it only has one optical transform and the joint power spectrum is directly input into a digital processing unit to compute the image shift. The local cross-correlation image can be directly obtained by adopting a local Fourier transform operator. After the pixel-level location of cross-correlation peak is initially obtained, the up-sampling technique is introduced to relocate the peak in even higher accuracy. With signal-to-noise ratio >= 20 dB, up-sampling factor k >= 10 and the maximum image shift <= 60 pixels, the root-mean-square error of motion measurement accuracy can be controlled below 0.05 pixels.