Enhancement of luminescence from encapsulated Si nanocrystals in SiO2 with rapid thermal anneals

Potentialities of rapid thermal annealing to enhance the photoluminescence emission of Si nanocrystals in SiO₂ have been investigated. Ion implantation was used to synthesize specimens of SiO₂ containing excess Si with different concentrations. Si precipitation to form nanocrystals in implanted samples takes place with a conventional furnace anneal. The photoluminescence intensity and the peak energy of emission from Si nanocrystals depend on implanted ion fluence. Moreover, the luminescence intensity is strongly enhanced with a rapid thermal anneal prior to a conventional furnace anneal. The luminescence intensity, however, decreases with a rapid thermal anneal following a conventional furnace anneal. It is found that the order of heat treatment is an important factor in intensities of the luminescence. Moreover, the luminescence peak energy is found to be dependent, but a little, on thermal history of specimens. Based on our experimental results, we discuss about the mechanism of an enhancement of the photoluminescence, together with the mechanism of photoemission from encapsulated Si nanocrystals produced in a SiO₂ matrix by ion implantation and annealing.     

Neuron-MOS Parallel Search Hardware for Real-Time Signal Processing

Circuit architecture for parallel data processing directly carried out on the hardware have been developed based on a high-functionality transistor, neuron MOSFET (neuMOS or MOS for short). In the MOS data sorting circuit, multiple analog input data are numbered in binary codes according to the order of their magnitudes after a single ramp voltage scan. A MOS motion-vector detector has been developed for on-chip moving image processing based on x- and y-projection data. The circuit can find the movement of an image in two successive frames within a few 100 nsec. The projection-data-based motion detection algorithm has been tested by computer simulation. Test circuits were fabricated by a double-polysilicon CMOS process and basic operation of the circuits has been demonstrated.     

Improvement of Dry EDM Characteristics Using Piezoelectric Actuator

This paper describes improvement of the machining characteristics of dry electrical discharge machining (dry EDM) by controlling the discharge gap distance using a piezoelectric actuator. Dry EDM is a new process characterized by small tool electrode wear, negligible damage generated on the machined surface, and significantly high material removal rate especially when oxygen gas is used. However, the narrow discharge gap length compared with conventional EDM using oil as the dielectric working fluid results in frequent occurrence of short circuiting which lowers material removal rate. A piezoelectric actuator with high frequency response was thus introduced to help control gap length of the EDM machine. To elucidate the effects of the piezoelectric actuator, an EDM performance simulator was newly developed to evaluate the machining stability and material removal rate of dry EDM.     

Novel self‐aligned top‐gate oxide TFT for AMOLED displays

Abstract— A novel highly reliable self‐aligned top‐gate oxide‐semiconductor thin‐film transistor (TFT) formed by using the aluminum (Al) reaction method has been developed. This TFT structure has advantages such as small‐sized TFTs, lower mask count, and small parasitic capacitance. The TFT with a 4‐μm channel length exhibited a field‐effect mobility of 21.6 cm²/V‐sec, a threshold voltage of ?1.2 V, and a subthreshold swing of 0.12 V/decade. Highly reliable TFTs were obtained after 300°C annealing without increasing the sheet resistivity of the source/drain region. A 9.9‐in.‐diagonal qHD AMOLED display was demonstrated with self‐aligned top‐gate oxide‐semiconductor TFTs for a low‐cost and ultra‐high‐definition OLED display. Excellent brightness uniformity could be achieved due to small parasitic capacitance.     

Influence of Sedimentation of Atoms on Structural and Thermoelectric Properties of Bi-Sb Alloys

Functionally graded thermoelectric materials (FGTMs) have been prepared by sedimentation of atoms under a strong gravitational field. Starting samples of Bi _x Sb_1?x alloys with different composition x were synthesized by melting of metals and subsequent annealing of quenched samples. The thermoelectric properties (Seebeck coefficient, electrical conductivity) of the starting materials were characterized over the temperature range from 300 K to 525 K. Strong gravity experiments were performed in a unique ultracentrifuge apparatus under acceleration of over 0.5 × 10⁶ G at temperatures of 538 K and 623 K. Changes of the microstructure and chemical composition were analyzed using scanning electron microscopy with energy-dispersive x-ray spectroscopy analysis. The distribution of the Seebeck coefficient of the Bi-Sb alloys was characterized by scanning thermoelectric microprobe. As a result of sedimentation, large changes in chemical composition (x = 0.45 to 1) were obtained. It was found that the changes in chemical composition were correlated with alterations of the Seebeck coefficient. The obtained experimental data allowed the development of a semiempirical model for the selection of optimal processing parameters for preparation of Bi-Sb alloys with required thermoelectric properties.     

Categorization of indoor places by combining local binary pattern histograms of range and reflectance data from laser range finders

This paper presents an approach to categorize typical places in indoor environments using 3D scans provided by a laser range finder. Examples of such places are offices, laboratories, or kitchens. In our method, we combine the range and reflectance data from the laser scan for the final categorization of places. Range and reflectance images are transformed into histograms of local binary patterns and combined into a single feature vector. This vector is later classified using support vector machines. The results of the presented experiments demonstrate the capability of our technique to categorize indoor places with high accuracy. We also show that the combination of range and reflectance information improves the final categorization results in comparison with a single modality.     

Comparative study of hydrophilic and hydrophobic ionic liquids for observing cultured human cells by scanning electron microscopy

An ionic liquid (IL) is a salt that remains in the liquid state at room temperature. It does not vaporize under vacuum and imparts electrical conductivity to samples for observation by scanning electron microscopy (SEM). Recently, the usefulness of ILs has been widely recognized. In our previous study, one of the ILs 1-ethyl-3-methylimidazolium tetrafluoroborate (EtMelm(+) BF(4)(-)) was used for SEM analysis of biological samples. In comparison with the conventional method, samples prepared using EtMelm(+) BF(4)(-) provided more detailed SEM images of the cell ultrastructure, enabling the observation of protrusions. In addition, the IL treatment is a less time consuming and simple method that does not include dehydration, drying, and conductivity treatments, which are an essential parts of the conventional method. In this study, we compared the usefulness of four hydrophobic and three hydrophilic ILs for SEM to observe fixed cultured human A549 cells. All ILs worked well to prevent "charge-up" effect for SEM observation. However, the hydrophilic ILs tended to provide clearer images than the hydrophobic ILs. We concluded that various ILs can be used for SEM sample preparation and their application to a wide range of fields is anticipated in future.     

Energy-less respiration monitoring device using thermo-sensitive film

We propose an easy-to-use energy-less respiration monitoring device for monitoring the breathing flow using a thermo-sensitive film. Thermo-sensitive film less than 0.01 mm thick with thermo-sensitive ink and a base film were wrapped over the aperture and partially produced in the tube for monitoring the breathing status. The aperture used as the respiration monitoring area, also worked as thermal isolation to shorten the response time and to decrease thermal capacity in the monitoring area. The response time was investigated using a response evaluation device (designed and produced using MEMS technology) to follow the temperature change with the breathing cycle of 0.3 Hz. The response time depended on the thickness of both the ink and the base film and decreased with the decrease of the thickness due to thermal capacity reduction. The obtained minimum response time was 373 ms when the ink thickness was 6.8 μm and the base film thickness was less than 5.0 μm. The color of the ink at the breathing monitoring area formed on the aperture successfully changed from blue to transparent according to the temperature change of the airflow.