Hitoshi Abe

Photostimulated molecular layer epitaxy

The quality of GaAs epitaxial layers prepared by molecular layer epitaxy (MLE) with and without UV light irradiation was studied and appears to be a promising method for preparing the GaAs thin layers with an atomic order accuracy. Namely, single layer‐by‐layer growth has been realized for GaAs using AsH3 and trimethyl (TMG), and triethyl (TEG), gallium. Substrate temperature of 500 °C for TMG and AsH3, and 300 °C for TEG and AsH3 fulfilled the conditions for monolayer growth, where the film growth thickness per cycle corresponding to 2.83 and 3.26 A for (100) and (111) B faces, respectively, are nearly saturated independently of the gas admittance quantity. Influences of photoirradiation on the film growth have been investigated by use of excimer lasers and Hg lamps. UV light irradiation improved the surface morphology and in certain instances also improved impurity concentrations. Conditioned photoirradiation—light beam synchronized with the time duration of AsH3 admittance, MO‐gas admittance, and evacu...

Gallium arsenide thin films by low‐temperature photochemical processes

Molecular layer epitaxy (MLE) is a new crystal‐growth method which is able to produce thin films of single crystal in the accuracy of atomic order at relatively low temperature. In MLE, adsorption and surface reaction processes are controlled by alternate injection of reactant gases. MLE of GaAs was demonstrated in trimethylgallium–AsH3 (TMG–AsH3) and triethylgallium–AsH3(TEG–AsH3) systems on various faces of GaAs substrate; monomolecular layer growth was realized for (100) face in TMG–AsH3 system. The film thickness, electric properties, and surface morphology were studied as a function of substrate surface crystalline orientations. By using mass spectroscopy, adsorption and surface reaction processes of MLE by TMG–AsH3 systems were studied. The formation and migration of Ga complex adsorbate which was produced from TMG, and the surface reaction of adsorbate with AsH3 were clarified. Influence of photoirradiation on the growing film has been investigated by use of excimer lasers. UV light irradiation imp...

Learning methodology of innovation architecture using case example of development of contactless palm vein pattern biometric authentication technology

The learning methodology for technology roadmapping (TRM) described in this paper comes out of the work of a Japan Techno-Economics Society group. A practical example of TRM is the innovation architecture (IA) proposed by H. Tschirkys group at ETH Zurich. A contrasting approach for an IA is to require engineers to learn the theoretical background before they customize the IA for particular applications. The IA users would have to make great efforts to interpret IA theory for their daily tasks, described in the language of their professions. The approach to designing a learning methodology in this paper is to build an IA using a case study. Using the case study, engineers are able to learn how to develop the IA by assuming the roles of project members. The paper covers the implementation of the methodology by describing how an IA is built using a case study on the development of a biometric authentication technology (released by Fujitsu Laboratories Ltd. in 2003). By using the methodology to follow the case example, an R&D organization was able to gain experience with the IA (TRM) and learn how to use it efficiently.

A superconducting-base hot-electron transistor (SBHET) using a high-Tc superconductor

The quantum mechanical reflection (QMR) at the interface between the high-Tc superconductor base and the semiconductor collector could be reduced to less than a few percent, if electrons are injected at energies close to the collector barrier. Values of fMAX are possible as high as 270 GHz and 400 GHz for SBHET Si and InAs by reducing the contact resistance of the semiconductor to as low as 10 Omega mu m2. The authors propose the use of ultra-thin metal films as layers to protect Si surfaces from oxidation and interdiffusion. BiSrCaCuO films on the Si(100) substrate covered with an Ag monolayer are deposited by the MBE method in two stages, the first is 1000 AA thick at Tsub=530 degrees C and the next 3000 AA thick at Tsub=700 degrees C, which showed the superconductivity, Tc approximately=20 K. Interdiffusion between the oxide films and Si substrate was hardly observed by AES depth analysis.

A challenge for service concept modeling by the Innovation Support Technology (IST)

Since autumn 2002, we have started a study group on Business Modeling at JATES (Japan Techno-Economics Society). The research of this study group is presently continued a study on the Innovation Support Technology (IST) which consists of a Business Modeling method, a strategic road mapping method and an Innovation Architecture (IA) method. These research activities have been reported in past PICMET conferences. Based on the previously proposed IST, the present paper discusses a framework that focuses on the development of service innovations: it describes a modeling method to systematically develop service business models and aims at providing engineers and researchers with a solid tool for new service developments.

Rubidium beam flux dependence of film properties of Ba1-xRbxBiO3 deposited by molecular-beam epitaxy using distilled ozone

We have focused our attention on the dependence of Ba1−xRbxBiO3 (BRBO) film composition ratio and film properties on rubidium‐beam‐flux intensity. BRBO films were deposited on MgO(100) substrates by molecular‐beam epitaxy (MBE) using distilled ozone. Systematic measurements showed that the rubidium content was nearly independent of rubidium‐beam‐flux intensity in a wide beam‐flux range. Therefore, it can be concluded that some degree of self‐control of rubidium stoichiometry is actually possible in BRBO film growth by MBE. This study also revealed that the BRBO film properties had strong dependences on rubidium‐beam‐flux intensity even in the range for self‐control of rubudium stoichiometry. Our study also clarified that rubidium‐beam flux affects the barium content in the BRBO film.

Electric Characteristics of High Tc Superconductor/Semiconductor Junction

We formed BiSrCaCuO and YBaCuO/Nb doped SrTiO3 (STO(Nb)) junctions. We measured current — voltage (I-V) characteristics and capacitance — voltage (C-V) characteristics of both junctions by varying temperature from 300K to 25K. Both samples clearly show the diode characteristics. Near room temperature the I-V curves of forward bias voltage show exponential dependence and the 1/C2(V) decrease linearly with voltage, thus following the usual Schottky relation. At lower temperature, however, the characteristics of samples differ from the Schottky relation.

Analysis of the high-frequency performance of high-Tc superconducting-base hot-electron transistors

Abstract We present an analysis of the high-frequency performance of semiconductor-superconductor-semiconductor superconducting-base hot-electron transistor (SBHET), in which the recently-discovered high- T c Cu-oxide (H T c Su) is introduced for the base material to allow a wide range of operating temperature. Two types of semiconductors, Si and InAs, with different temperature dependences of electrical properties are investigated for the emitter and collector. The quantum mechanical reflection (QMR) at the interface between the H T c Su base and collector indicates that electrons should be injected at energies close to the collector barrier. This makes it easy to reduce QMR by using the same semiconductor for both the emitter and collector. From results of the QMR and the mean free path of the H T c Su determined from an experiment, the current gain α 0 for the 100 A base is estimated to be 0.3–0.6, depending on the temperature. The emitter-charging time and collector-transit time are calculated to obtain the result that the achievable cut-off frequency f T of the SBHET with Si and InAs are about 40 and 90 GHz, respectively. With α 0 and f T thus determined, the maximum oscillation frequency f max is evaluated by means of a circuit model including parasitic effects. It is found that f max as high as 230 and 320 GHz are possible for the SBHET with Si and InAs, respectively, when the contact resistance of semiconductors is reduced to 10 Ωμm 2 .

Thin Film, OMCVD Process for High-Tc Superconductivity

This paper describes the potentiality of the OMCVD method for a high-Tc thin film formation technique. At the beginning of 1988, Naval Research Institute, Tohoku University and Oki Electric have independently succeeded in the high-Tc ceramics film formation by the OMCVD method. Y-Ba-Cu-O films could be prepared with a quality of Tc higher than 90K and Jc=1.9x106A/cm2 at 77K, which is comparable to that obtained by sputtering or MBE method. Basic studies on the OMCVD deposition process of high-Tc films have been done. Very recently, by using N2O as an oxygen source, we have succeeded in radically reducing the temperature of film formation.

PPP (Public Private Partnership) frontier; a study on Local Abenomics driven social innovation

Local Abenomics vitalizing local economy is one of the most important political issues in Japan. SMEs and micro enterprises have supported the local economy until today. They have rooted in the community and provided employment basis. Job creation in rural areas was chosen as the key problem to be solved, while strengthening “earning power” of regional industries is essential to promote a virtuous cycle between communities, people and work. From this stand point, we studied local 10,000 projects and proposed problem solving methods as PPPs and local innovation ecosystem. 287 projects have been started by Ministry of Internal Affairs and Communications. Four performance indexes as financing amount, local job creation, local resources utilization, and cash flow creation were selected and evaluated. We analyzed some of 287 projects by MOT tools (innovation ecosystem, business model) and report validity and effectiveness of policy making contents. This study has been done in a group of SMECA (Japan Small and Medium Enterprise Management Consultant Association) since 2015 summer.