Eiichi Maruyama

Amorphous Built-in-Field Effect Photoreceptors

Thin-film photodiodes with the graded-composition structures of amorphous Se–As–Te have been developed. The physical mechanism of the buit-in-field effect in these highly resistive photodiodes has been clarified. In order to realize complicated composition distributions, multi-layer evaporation technology has also been developed. The physical properties of multi-layered films and those of the uniform amorphous film have been compared, and it has been shown that a multi-layered film of 1 nm periodicity can be regarded as an almost uniform amorphous material. Built-in-field effect photoreceptors can be utilized not only for TV pickup tubes but also for highly sensitive xerographic plate and other solid-state sensors.

Photoconductive imaging using hydrogenated amorphous silicon film

Highly resistive hydrogenated amorphous‐silicon film has been fabricated and examined as blocking‐type photoconductive target of a vidicon‐type image pickup tube. The results indicate that this novel silicon vidicon has many advantages over conventional ones.

Polycrystalline‐silicon thin‐film transistors on glass

Thin‐film transistors are fabricated on polycrystalline silicon on transparent glass using molecular beam deposition at low temperatures. It is found that the transistor characteristics and stability of this device, together with the low‐temperature processes utilized, afford potential application to flat display panels.

Low‐temperature formation of polycrystalline silicon films by molecular beam deposition

Textured polycrystalline‐silicon films are obtained by molecular beam deposition under ultrahigh vacuum at temperatures between 400 and 700 °C. Thinner films have a 〈110〉 preferred orientation, whereas a 〈100〉 preferred orientation is dominant in films with a thickness of above 1 μm. The deviation of the textured axes decreases from 20° to 10° with raising substrate temperature from 400 to 700 °C. A depth‐dependent preferred orientation inside the film is also observed.

Thin‐film transistors on molecular‐beam‐deposited polycrystalline silicon

Thin‐film transistors (TFT’s) have been fabricated on molecular‐beam‐deposited (MBD) polycrystalline silicon (poly‐Si) on transparent glass substrates using low temperature (below 600 °C) processes. The field‐effect mobility of the TFT is 40 cm2/V s at a gate voltage of 10 V, and the response time is less than 10 ns. Output characteristics of the TFT’s depend on the poly‐Si film thickness. The threshold gate voltage and the field‐effect mobility become lower and higher, respectively, with increasing film thickness. These results can be explained in terms of the thickness‐dependent crystallinity of the surface region in the MBD poly‐Si film. A 10×10 TFT matrix has been fabricated, and by combining the TFT matrix with a twisted‐nematic liquid‐crystal layer, a transmissive‐type active matrix liquid‐crystal display panel has been fabricated. This poly‐Si TFT matrix has proved to be compatible with a liquid‐crystal cell from the viewpoints of both device fabrication and transistor characteristics.

Raman scattering in low wavenumber region as a new probe to structural properties of microcrystalline silicon

Abstract The structural properties of microcrystalline silicon (μc-Si) are studied by Raman scattering. It is found that the intensity of each Raman band closely correlates with the absorption coefficient in the interband region and that the Raman band at ca. 150 cm −1 is a sensitive probe to randomness of Si-Si bonding structure in μc-Si.

A Contact Type Linear Photodiode Array Using an Amorphous Thin Film

A Contact type linearly arrayed imaging sensor not requiring an optical lens system has been successfully developed. This sensor array consists of 40 amorphous Saticon type photodiodes formed on an optical fiber plate, each of which measures 250 µm by 200 µm and the overall sensor length is 10 mm. This device has an advantage of easy fabrication which permits elongation of the total length without deteriorating the high resolution characteristics. Therefore, it may be useful as an imaging sensor for small size facsimile equipment. In this paper, a series of technical data on the proposed structure, the fabrication procedures and also the static and operational performances are described.

A 10×10 Polycrystalline-Silicon Thin-Film Transistor Matrix for Liquid-Crystal Display

A 10×10 thin-film transistor (TFT) matrix has been fabricated using a molecular beam deposited polycrystalline silicon film on a glass substrate by low-temperature (below 600°C) fabrication processes. The field-effect mobility of the TFT element is 40 cm2/Vs at a gate voltage of 10 V, and the response time is less than 10 ns. Combining the TFT matrix with a twisted-nematic liquid-crystal layer, a transmissive-type active matrix liquid-crystal display. It has been shown that the polycrystalline silicon TFT matrix is compatible with a liquid-crystal cell both from the viewpoint of device fabrication and of TFT characteristics.

A highly sensitive chalcogenide photoconductor in a near‐infrared wavelength region

A new highly sensitive photoconductor in a near‐infrared wavelength region with a low dark decay has been developed for an electrophotographic device. The photoconductor has been created with a multilayered Se‐As‐Te chalcogenide glass. The structure of the photoconductive layer consists of four parts: (a) Se‐rich blocking layer, (b) Te‐rich IR‐sensitive layer, (c) As‐rich space‐charge layer, and (d) Se‐rich voltage sustaining layer. A Cerium oxide layer is interposed as a carrier blocking layer on the substrate. This photoconductor has shown sensitivity of about 300 m2/J to beams having a wavelength of 750 nm. This sensitivity is as high as that of the amorphous Se photoconductor to light having a wavelength of 442 nm. This photoconductor has favorable characteristics such as a high initial surface potential, low dark decay, low residual surface potential, and long durability in practical use. It is suitable for a photoconductor in a laser beam printer with a diode laser.

Striped optical filters composed of multi-layered TiO2 and SiO2 films deposited by RF sputtering

Abstract Striped optical filters (cyan, magenta and yellow) are fabricated using a multi-target RF sputtering apparatus. These filters are made of 13 layers of TiO 2 and SiO 2 , with refractive indices of 2.50 and 1.47, respectively, at 546.1 nm. The spectra for these filters do not shift more than ±2 nm after baking at 500°C for 1 h in air. The filter layers are deposited alternately in one pump-down vacuum. The pitch, length and number of stripes are 20 micro m, 10 mm and about 700 lines respectively. The stripes are photoetched with conventional lift-off techniques, using two layers of Al and Cr. Each layer is deposited by placing the substrate holder under the TiO 2 and SiO 2 target for appropriate time intervals calculated from the deposition rate. Deviations in the deposition rate are within ±2%, as the result of automatically controlling RF power and sputtering gas pressure. The electric signal output from each color channel of these striped filters in tri-electrode pickup tube is increased by 6 dB over that of conventional R, G and B filters. The related moire signal-to-noise ratio has been decreased by 6 dB.