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Ultrathin silicide with thickness less than 30 nm and specific contact resistivity to silicon less than mid-10/sup -7//spl Omega/-cm/sup 2/ is necessary for achieving low contact resistance in a sub-0.25-/spl mu/m fully-depleted (FD) silicon-on-insulator (SOI) CMOS technology. This contact problem becomes even more severe as one continues to scale down the device dimensions. We first studied the effects of source/drain series resistance and gate sheet resistance on the device speed performance and obtained a set of desired design criteria. These were used along with a transmission line model to yield a silicide design space, which was then used to evaluate the experimental results. Both cobalt and titanium silicide processes were implemented and found to satisfy the design criteria. Final device characteristics were also measured. Several process integration issues related to contact dielectric deposition and contact barrier integrity were found to greatly impact the final contact properties. These along with the detailed fabrication process are discussed.

A colorful see through BIPV module with high power output and pretty appearance is demonstrated in this study. Different thin reflective layers (patent pending) are employed to create desired colorful appearance and fully integrated with production process. Several colorful modules, such as purple, dark blue, light blue, silver, golden, orange, maroon and chocolate, have been developed. The highest power of this module is 108W and the highest transmittance is almost 20%.

Vacuum metal deposition (VMD) utilizing sequential Au and Zn depositions has been an effective technique to develop latent fingerprint on plastic surfaces. A simplified vacuum deposition process was conducted to develop fingerprint in this study. While pure ZnO was thermally evaporated in a vacuum system, ZnO could condense on polyethylene terephthalate (PET) surface. Direct deposition of ZnO, without applying Au seeding, yielded normal development of latent fingerprint. The development of aged fingerprint by ZnO deposition was more effective than that by Au/Zn VMD.

Diamond crystallites were nucleated and grown from the vapor phase on silicon substrates previously processed into arrays of nanometer‐scale silicon wires. We found that the nanowires did not aid nucleation, and that the nucleation density on the nanowire base was very low (

The ability to control structural dimensions below 5 nm is essential for a systematic study of the optical and electrical properties of Si nanostructures. A combination of electron beam lithography, NF3 reactive ion etching, and dry thermal oxidation has been successfully implemented to yield 2‐nm‐wide Si nanowires with aspect ratio of more than 100 to 1. With a sideview transmission electron microscopy technique, the oxidation progression of Si nanowires was characterized over a range of temperature from 800 to 1200 °C. A previously reported self‐limiting oxidation phenomenon was found to occur only for oxidation temperatures below 950 °C. A preliminary model suggests that increase in the activation energy of oxidant diffusivity in a highly stressed oxide may be the main mechanism for slowing down the oxidation rate in the self‐limiting regime.

Titanium silicide films grown on silicon were analyzed by transmission electron microscopy (TEM), electron diffraction, scanning transmission electron microscopy (STEM), energy dispersive x-ray spectroscopy, and electron energy loss spectroscopy. The films were prepared by sequential rapid thermal annealing (RTA) at 675 °C and 850 °C of 16-nm-thick sputtered Ti on Si (001) wafers. In some cases, a 20-nm-thick TiN capping layer was deposited on the Ti film before the RTA procedure and was removed after annealing. HRTEM and STEM analysis showed that the silicide films were less than 0.1 μm thick. The capped film was more uniform, ranging in thickness from ∼25–45 nm, while the uncapped film ranged in thickness from ∼15–75 nm. Electron diffraction was used to investigate the titanium silicide phases present in the films; more than one phase was found to exist.

Titanium silicide films grown on silicon were analyzed by transmission electron microscopy (TEM), electron diffraction, scanning transmission electron microscopy (STEM), and energy dispersive x-ray spectroscopy. The films were prepared by sequential rapid thermal annealing (RTA) at 675 °C and 850 °C of 16-nm-thick sputtered Ti on Si (001) wafers. In some cases, a 20-nm-thick TiN capping layer was deposited on the Ti film before the RTA procedure and was removed after annealing. TEM and STEM analyses showed that the silicide films were less than 0.1 μm thick; the capped film was more uniform, ranging in thickness from ∼ 25 – 45 nm, while the uncapped film ranged in thickness from ∼ 15 – 75 nm. Electron diffraction was used to determine that the capped film contained C54-TiSi2, C49-TiSi2, Ti5Si3, and possibly TiSi, and that the uncapped film contained C49-TiSi2, TiSi, Ti5Si3, unreacted Ti, and possibly C54-TiSi2.

Although photorefractive materials are those that exhibit both appreciable electro-optic and photoconductive behavior, the chromophore parameters that lead to large electro-optic coefficients have not so far led to similar photorefractive performance. Recently, it has been shown that the electro- optic contribution is one of two principal contributions to the overall photorefractive behavior, and that it is usually the smaller of the two. The larger factor, first referred to in the literature as an 'orientational enhancement,' is due to the birefringence of the chromophore: the difference in polarizability parallel to the dipole moment and perpendicular to it. A figure of merit incorporating both effects has been derived, although its determination is more difficult than that for purely electro-optic materials. The polarizability anisotropy is a function of all three components of the diagonalized polarizability tensor. Two expressions for these three parameters can be obtained by index of refraction and light scattering measurements on chromophores in solution. The third must be estimated. Results from this new characterization protocol are presented and compared with the results of photorefractive experiments on materials containing the tested chromophores. Another class of compounds has also been found to be of potential use in holographic storage, in this case write- once applications. These chromophores undergo an irreversible photochromic reaction that is triplet sensitized. A mechanism is proposed for this reaction and supporting data provided.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Materials to be used for optoelectronic, photorefractive, or frequency doubling applications must have high nonlinearities, good thermal stabilities, and low optical loss (high transparency). Organic compounds synthesized for incorporation into poled nonlinear polymers typically exhibit tradeoffs between nonlinearity and each of the other two qualities. By judicious use of arylamino donor groups and cyano-containing acceptor groups, a small set of chromophores that are both highly nonlinear and stable at high temperatures has been prepared. By selecting delocalized bridging moieties that are either tuned for optimum hyperpolarizability or exhibit two charge-transfer excited states, highly transparent chromopohores with excellent nonlinearities can be prepared. The results suggest that thermal stability and nonlinearity are jointly achieved by modifying donor and acceptor groups, while transparency and nonlinearity are jointly achieved by modifying bridging groups.

Understanding the electronic structures of silicon (Si) nanostructures is essential for exploring their potential applications in opto-electronics. Well behaved and ordered Si nanostrctures are desirable for facilitating the characterization process and the interpretation of experimental results. A combination of high resolution electron beam lithography, anisotropic reactive ion etching (RIE), and thermal oxidation was shown to yield such well behaved Si nanostructures [1][2]. Etched Si nano-wires with diameters less than 20 nm and aspect ratios greater than 20 were fabricated using a RIE process based on NF3 plasma. Thermal oxidation was demonstrated to be a feasible technique for reducing the diameter of the Si nano-wires to below 5 nm. A transmission electron microscopy (TEM) technique was developed to obtain precise structural information from these oxidized Si nanostructures and to study other interesting oxidation related phenomena. A feasible electrical contact technique was proposed and preliminary contact characteristics were obtained. All of these constitute an important first step toward understanding the intrinsic properties of Si nanostructures.

Fabricating well controlled nanostructures and obtaining precise structural, electrical, and optical information from them are essential for understanding die intrinsic properties of silicon (Si) nanostructures, which in turn is important for exploring the potential of quantum confinement induced light emission from crystalline Si. A combination of high resolution electron beam lithography, anisotropic reactive ion etching (RIE), and thermal oxidation has been successfully applied to obtain sub-5 nm Si columnar structures [1]. A transmission electron microscopy (TEM) technique has also been used to characterize die precise structural dimensions of these columns [1]. To obtain the electrical and optical information, a process based on polyimide planarization was developed to establish electrical contacts to these nanostructures. The same process is also applicable for fabricating device structures to study electrically pumped optical response. Preliminary transport studies have confirmed current conduction through die Si nano-pillars and yielded an estimate of die conductivity.

The valence band and the Si 2p core level of electrochemically etched light emitting porous silicon samples prepared with different etching parameters and upon thermal annealing have been studied. The core level shows appreciable broadening as chemical etching time increases. Upon annealing, the core level linewidth decreases and the valence band develops spectral features. The photoluminescence intensity, also, decreases upon annealing. However, impurity species are found to be present only in trace amounts. Our data is consistent with a photoluminescence mechanism involving a silicon species that degrades, decomposes, or desorbs upon annealing.

Recently it was shown that birefringence caused by orientation of chromophores with anisotropic polarizabilities contributes more to the photorefractive effect in in situ poled organic materials than do the electro-optic properties of the chromophores. A figure of merit specific to photorefractive applications has been derived, and an experimental procedure for its determination is described in detail. The figure of merit is evaluated for the chromophores used in four of the most historically important photorefractive polymers. The chromophore figures of merit and photorefractive material performances are compared and contrasted.

Achieving tolerances of the order of 1 nm for sub‐10 nm structures is both challenging and necessary for controlled experiments on such structures. Here the use of a self‐limiting oxidation reaction to yield silicon (Si) wires of less than 10 nm diam with a tolerance of ±1 nm over 0.5 μm. The final self‐limiting diameters were found to be controlled by oxidation temperature. For 30 nm initial Si column diameters, the asymptotic diameters were found to be 11 and 6 nm for dry oxidation at 800 and 850 °C, respectively. The mechanism of the self‐limiting reaction is not yet fully understood but the tiny radius of curvature is obviously a factor. In addition, there appears to be an anomalous loss of Si; this may be due to sublimation of SiO.

Understanding the optical and electrical properties of Si nanostructures is essential for exploring the potential of using structural quantum confinement to induce light emission from crystalline Si. To this end, sub‐50 nm Si columns were fabricated with high resolution electron beam lithography and anisotropic reactive ion etching. The dimensions of the Si nanostructures were further reduced by thermal oxidation. A novel transmission electron microscopy technique was developed to monitor the oxidation progress without removing the oxide structural support. Images of sub‐5 nm crystalline Si cores were obtained. The oxidation rates of the Si nanostructures were characterized. Among the various interesting oxidation phenomena are the nonmonotonic oxidation rate with respect to the column size and an unexpectedly slow change of the outer diameters of the oxidized columns. Several likely mechanisms, including the stress retardation of oxidation for a small radius of curvature, the stress induced generation an...