Experimental investigation of parallel optical data storage using pyrrylfulgide photochromic material

The optical storage characteristics of a new kind of organic photochromic material-pyrrylfulgide were experimentally investigated in the established parallel optical data storage system. Using the pyrrylfulgide/PMMA film as a photon-mode recording medium, micro-images and encoded binary digital data were recorded, readout and erased in this parallel system. The storage density currently reaches 3 x 10(7) bit/cm(2). The recorded information on the film can be kept for years in darkness at room temperature.

Preparation and optical property of a novel hydrophobic anti-reflection coating for KDP crystal

A novel inorganic-organic hybrid hydrophobic anti-reflection silica film used for laser crystal was obtained by sol-gel process. The film consisted of silica sols mixed with a small amount of polymethyl methacrylate (PMMA) or polystyrene (PS). The optical transparency, hydrophobic property and surface morphology of the film were characterized by UV-VIS-NIR spectrophotometer; contact angle instrument and Scanning Electron Microscopy (SEM), respectively. The results showed that the anti-reflection coating had good hydrophobility and optical transparency from 400 nm to 1200 nm. The contact angle reached to 130-140 degrees. SEM images indicated the hydrophobic films modified with PMMA or PS had compact structure compared to the pure silica sol film. (C) 2008 Elsevier B.V. All rights reserved.

STUDIES OF THE PROMISING MATERIAL COSI2 ON GAAS SUBSTRATES

The thermal stability of CoSi2 thin films on GaAs substrates has been studied using a variety of techniques. The CoSi2 thin films were formed by depositing Co(500 angstrom) and Si(1800 angstrom) layers on GaAs substrates by electron-beam evaporation followed by annealing processes, where the Si inter-layer was used as a diffusion/reaction barrier at the interface. The resistivity of CoSi2 thin films formed is about 30 muOMEGA cm. The Schottky barrier height of CoSi2/n-GaAs is 0.76 eV and the ideality factor is 1.14 after annealing at 750-degrees-C for 30 min. The CoSi2/GaAs interface is determined to be thermally stable and the thin film morphologically uniform on GaAs after 900-degrees-C/30 s anneal. The CoSi2 thin films fulfill the requirements in GaAs self-aligned gate technology.

A COMPARATIVELY LOW-QUALITY SILICON MATERIAL IMPROVED FOR SOLAR-CELL FABRICATION

A comparatively low-quality silicon wafer (with a purity of almost-equal-to 99.9%) was adopted to form a silicon-on-defect-layer (SODL) structure featuring improved crystalline silicon near the defect layer (DL) by means of proton implantation and subsequent annealing. Thus, the SODL technique provides an opportunity to enable low-quality silicon wafers to be used for fabrication of low-cost solar cells.

NEW TYPE OF SILICON MATERIAL WITH VERY HIGH-QUALITY SURFACE-LAYER ON INSULATING DEFECT LAYER

A new-type silicon material, silicon on defect layer (SODL) was proved to have a very high quality surface microstructure which is necessary for commercially feasible high-density very large scale integrated circuits (VLSI). The structure of the SODL material was viewed by transmission electron microscopy. The SODL material was also proved to have a buried defect layer with an insulating resistivity of 5.7 x 10(10) OMEGA-cm.

INVESTIGATION OF GAAS/SI MATERIAL BY X-RAY DOUBLE-CRYSTAL DIFFRACTION

GaAs epilayer films on Si substrates grown by molecular-beam epitaxy were investigated by the x-ray double-crystal diffraction method. The rocking curves were recorded for different diffraction vectors of samples. The results show that the unit-cell volumes of GaAs epilayers are smaller than that of the GaAs bulk material. The strained-layer superlattice buffer layer can improve the quality of the film, especially in the surface lamella. The parameter W' = W(expt)/(square-root \gamma-h\/gamma-0/sin 2-theta-B) is introduced to describe the quality of different depths of epilayers. As the x-ray incident angle is increased, W' also increases, that is, the quality of the film deteriorates with increasing penetration distance of the x-ray beam. Therefore, W' can be considered as a parameter that describes the degree of perfection of the epilayer along the depth below the surface. The cross-section transmission electron microscopy observations agree with the results of x-ray double-crystal diffraction.

PROTON-IMPLANTED NEW TYPE SILICON MATERIAL SUBJECTED TO 2-STEP FURNACE ANNEALING

A high-resistivity defect layer buried beneath the silicon surface layer by using proton implantation and two-step conventional furnace annealing is described. During the first annealing step (600-degrees-C), implanted hydrogen atoms move towards the damage region and then coalesce into hydrogen gas bubbles at the residual defect layer. During the second annealing step (1180-degrees-C) these bubbles do not move due to their large volume. Structural defects are formed around the bubbles at a depth of approximately 0.5-mu-m. The defect layer results in a high resistivity value. Experiments show that the quality of the surface layer has been improved because the surface Hall mobility increased by 20%. The sample was investigated by transmission electron microscopy.