Tetsuya Ohshima

Ultra-High-Sensitive Image Pickup Tubes Using Avalanche Multiplication in a-Se.

Extremely high-sensitive image pickup tubes with sensitivities 1000 times higher than those of conventional tubes are fabricated using the avalanche phenomenon in a-Se as photoconductive targets. The excess avalanche noise of a video signal is found to be much less than that expected, based on the carrier ionization rates. The frequency spectra of the noise currents of both the pickup tubes and sandwich-type photocells are examined. The results are compared with those of a simulation, and it is found that the excess noise can be reduced by the charge-storage operation of imaging devices.

Excess Noise in Amorphous Selenium Avalanche Photodiodes

Excess noise in amorphous Selenium avalanche photodiodes (a-Se APD) has been measured in a frequency range from 3 kHz to 30 kHz. The deduced excess noise factors, including dependences on photocurrent, frequency, applied electric field and the a-Se layers thickness, agreed with McIntyres theoretical values.

High quality NiSi2/Si epitaxial films grown by MBE

Abstract The correlation between Schottky contact properties of epitaxially grown NiSi 2 and its growth conditions is studies. A strong dependence of the Schottky barrier height and ideality factor upon the surface morphology, which is strongly affected by the growth condition, is found. It is verified that uniform NiSi 2 film can be grown at temperatures lower than 600°C by both methods og MBE and solid phase epitaxy from Ni/Si multi-layers. The smooth NiSi 2 films grown here are confirmed to give good Schottky characteristics.

Desktop autostereoscopic display using compact LED projector

A stereoscopic display using a curved directional reflection (CDR) screen and projectors is a promising approach towards realizing an immersive three-dimensional (3D) display system. The CDR screen consists of a corner reflective mirror sheet for horizontal focusing and an anisotropic diffuser sheet for vertical diffusion. The CDR 3D display can provide bright and large images without the need for special glasses. In this paper, we introduce this immersive 3D display technique onto the desktop display. To realize this concept, we have developed the compact projectors with light emitting diode (LED) light sources and a liquid crystal on silicon (LCOS). These have allowed the realization of 65 mm width projectors that are able to be put side by side at the interocular distance. The efficient optical system of an LED array as area-light-sources combined with an ultra high gain (>100) CDR screen have allowed for a desktop autostereoscopic display whose luminance is more than 100 cd/m2 with only 9 W power consumption. This system provides immersive 3D images for only the observer and keeps his privacy.

Self-aligned NiSi2 electrode fabrication by MBE and its application to etched-groove Permeable Base Transistor (PBT)

Abstract A self-aligned NiSi 2 electrode fabrication process was developed. Epitaxial NiSi 2 films were selectively grown on a Si substrate by MBE with a thin SiO 2 film mask. NiSi 2 electrodes were fabricated simultaneously on the bottom and the top surfaces of grooved Si substrates in a self-aligned manner. These electrodes showed good Schottky characteristics. By using this method, etched-groove permeable base transistors (PBTs) were fabricated, where the NiSi 2 layers on the etched grooves were used as gate and source electrodes. The highest mutual conductance ( g m ) was obtained as 32 mS/mm, which agreed well with the results of computer simulation.

An observation of 650 °C deformation of Si surface under ultra high vacuum

Significant deformation of a grooved Si surface is discovered during low temperature processing (650–900 °C) in a ultra high vacuum. The lowest temperature at which deformation results is determined to be 650 °C for a (111)Si substrate. In addition, clear facets are formed after high temperature processing (850–900 °C). These new findings are tentatively considered to originate from the surface migration of Si atoms on atomically clean surfaces.

55.3: Desktop Autostereoscopic Display Using Compact LED Projectors and CDR Screen

We have developed a 20” desktop autostereoscopic projection display using a Curved-Directional-Reflection (CDR) screen. A liquid crystal on silicon (LCOS) and light emitting diode (LED) light sources have allowed the realization of compact 65 mm width projectors that are able to be put side by side at the interocular distance. The efficient optical system of an LED array as area-light-sources combined with an ultra high gain (<100) CDR screen have allowed for a desktop autostereoscopic display whose luminance is more than 100 cd/m2 with only 9 W power consumption.

Evaluation of Electrophoretic Migration of Submicron Particles in a Microgap by Optical and Current Responses

We studied the electrophoretic migrations of submicron particles in nonpolar inks sealed in narrow gap cells of 5.3 µm by using optical and current responses. We evaluated the mobility of particles by using the optical responses of the total reflection at interfaces between electrodes and the solvent in addition to simultaneously measuring current, from which the concentrations of ions and charged particles were analyzed. The mobility of the particles in the narrow gap was similar to that of the bulk ink, except for the case with no charge director and less dependence on the charge director concentration. We also analyzed how the mobility was distributed and how the particles interacted with the interface by using the optical responses.

High speed Si PBT with buried single crystal silicide electrode by MBE

Silicon permeable base transistors (PBTs) with buried single-crystal electrodes were fabricated by developing formation techniques using molecular beam epitaxy (MBE) for obtaining single-crystal-Si/silicide/Si double-heterostructures and silicide films in submicron size patterns. A high transconductance of 50 mS/mm and high current density of 2*10/sup 4/ A/cm/sup 2/ were obtained. The highest unity current gain frequency (f/sub T/) 6 GHz. Computer simulations indicated that the value of f/sub T/ was reasonable and could be improved by more than one order of magnitude (about 120 GHz) by optimizing the device structure.<<ETX>>

Evaluation of Electrophoretic Migration by Optical and Current Responses to Cyclic-Polarity-Reversed Triangular Voltage

We studied the electrophoretic migration of electrophoretic inks by measuring the total reflection at the interface between the electrode and the ink solvent simultaneous with the current response to a cyclic-polarity-reversed triangular voltage. We demonstrated that the current peaks and optical responses to the cyclic-polarity-reversed triangular voltage are effective for the easy evaluation of mobility, the charge amount of ions and ink particles, and the interactions of particles with the electrode and inter-particles. The mobility of the ink particles was measured from the slopes of these peak voltages as functions of the square root of the time rate of the scanning voltage. The offset of line extrapolation indicated the interaction of the particles with the electrode. The optical response was effective for measuring the mobility even when the conductivity of the cell was too large to detect the drift current peaks.