Ryuhei Kimura

Studies on necessary condition of companion robot in the RAA application

This paper describes desirable properties that the companion robots should have for the application to robot assisted activity / robot assisted therapy (RAA/RAT) from the standpoint of robotics. Although animal assisted activity / robot assisted therapy (AAA/AAT) give us much better effectiveness in the hospital and old-peoples nursing home for the present time, these institutes have been looking forward to RAA/RAT because of difficulties in AAA/AAT in handling of living animals and prevention of epidemics. From the fieldwork in pediatrics ward and the nursing home using the robots on-the-market that can be partly brought up, we extracted what kind of function is effective in communication between patient-robot, patient-nurse, and patient-patient. This paper also mentions how to actualize such function by software modeling and programming.

PHOTOLUMINESCENCE PROPERTIES OF SODIUM INCORPORATED IN CUINSE2 THIN FILMS

CuInSe2 films with Cu/In ratios of m=0.83–0.99 have been deposited on glass substrates by the co-evaporation method using a bi-layer process. The effects of sodium in these films have been investigated by comparing the electrical and optical properties of the films with and without the Na2Se incorporation. Two donor-acceptor pair emissions, [D, A]α at 0.89–0.94 eV and [D, A]β at 0.84–0.87 eV, were typically observed in the photoluminescence spectra. The relative intensity of [D, A]α to [D, A]β was found to depend strongly on both the Cu/In ratio and Na incorporation. For the films with m=0.94, [D, A]α was predominantly observed regardless of Na incorporation. For m≤0.90, [D, A]β became dominant for the films without Na, while [D, A]α remained as the dominant emission for the films with Na. A correlation between the prominence of [D, A]α and resistivities below 2×103 Ω cm was found, suggesting a reduced compensation by suppressed Se vacancy donors due to the presence of Na.

Preparation of GaAs and Ga1−xAlxAs multi-layer structures by metalorganic molecular beam epitaxy

Metalorganic molecular beam epitaxial (MOMBE) growth of GaAs and (GaAl)As using triethylgallium (TEG) and triethylaluminum (TEA) has been studied. N-GaAs/p-GaAs multi-layer structures were prepared by applying an alternating ionization voltage to hydrogen. Single-crystal Ga1-xAlxAs ternary alloy with good surface mophology was successfully grown by introducing TEA as an Al source. The epitaxial layers typically showed p-type conduction with a carrier concentration of more than 1018 cm-3, this being due to residual carbon. A (GaAl)As/GaAs multiquantum well (MQW) heterostructure was fabricated by switching TEA and it was observed that the photoluminescence peak energies from the MQW structures were shifted to the higher energy position. Furthermore, selective growth of GaAs and (GaAl)As on a partly SiO2 masked GaAs substrate was investigated. In the MOMBE growth of (GaAl)As, polycrystalline film was deposited on the SiO2 masked region, while no deposition took place in the growth of GaAs.

Effects of Sodium on CuIn3Se5 Thin Films

CuIn3Se5 films have been deposited with Na2S on Coning 7059 glass substrates by the two-stage co-evaporation method. Stoichiometric CuIn3Se5 films with p-type conduction with the resistivities of 106 Ωcm range were obtained by our sodium control technique. Enhanced grain growth and preferred (112) orientation were also clearly observed with sodium incorporation; the same effect that has been reported for chalcopyrite CuInSe2 thin films. The effects of sodium in these films have been investigated by comparing the electrical and optical properties of CuIn3Se5 films with and without the Na incorporation. A correlation between the photoluminescence spectra and the resistivity or conduction type of the CuIn3Se5 films was found, suggesting a reduction in compensation due to the suppression of donor-type defects by the presence of Na.

Molecular Beam Epitaxial Growth of GaN on (0001) Al2O3 Using an Ultrathin Amorphous Buffer Layer Deposited at Low Temperature

The effects of buffer layer quality and/or deposition conditions on the molecular beam epitaxy of GaN on c-Al2O3 substrates were investigated. In order to precisely determine the effects of a thin buffer layer, atomically flat and monolayer-stepped Al2O3 substrates were prepared by conventional chemical etching with a H3PO4: H2SO4 solution. A significant improvement in the crystalline quality of the GaN epilayer was achieved when ultrathin amorphous buffer layers deposited at temperatures as low as 125°C were used. It was found that low-temperature deposition leading to an amorphous buffer layer is important for the optimization of the subsequent GaN epitaxial layer. The thickness of the buffer layer is critical; only a very thin amorphous layer can be well crystallized during the thermal annealing process before epilayer growth. It was found that GaN epilayers grown on this buffer layer gave rise to band-edge emissions (357 nm/FWHM=19.7 meV) without any deep emissions in low-temperature photoluminescence and led to (0002) X-ray rocking curves with a full-width at half maximum of about 9.8 arcmin.

High-purity cubic GaN grown on a AlGaAs buffer layer by molecular beam epitaxy

Abstract High-purity cubic GaN films have been successfully grown on a AlGaAs buffer layer by molecular beam epitaxy. A characteristic nitrided AlGaAs smooth faceted surface was observed. It was found that GaN epilayers grown on a nitrided Al 0.17 Ga 0.83 As buffer layer were epitaxial and contained only the cubic phase. No diffraction peaks associated with the hexagonal phase of GaN were observed by X-ray pole-figure measurements.

Investigation of playing with entertainment robotic pet of pre-school aged child in nursery school by video observation

In order to investigate Human (pre-school aged child; 4-6 years old) - robot interaction (HRI), entertainment robotic pet; AIBO, mental commit seal robot; PARO, and communication robot; ifbot were introduced into childs playing in classroom environment of nursery school. Videotaping was carried out for behavioral analysis to observe childs playing with robot and consider childs recognition of robot. By this analysis, it is thought that child seemed to felt imperfect consciousness, but did not accept robot as living thing. They recognized robot as artificial emotional creature.

Comparison of the Reaction Time Measurement System for Evaluating Robot Assisted Activities

RAA (Robot Assisted Activities) allow people to feel joy and pleasure and recover through contact with a robot. Considerable research has reported that RAA is useful for elderly persons, children hospitalized in pediatric wards and so on. However no specific evaluation method concerning RAA has yet been established. In this paper, we propose a reaction time measurement system for evaluating RAA. The level of caution or concentration of a subject can be estimated in terms of the reaction time based on visual or acoustic stimuli. We try to evaluate RAA using the variance in the reaction time before and after RAA respectively. We have developed a reaction time measurement system with hardware, following which we compared several reaction time measurement systems concerning performance and operability. We reported the results of comparisons featuring such measurement systems and the basic results of the RAA evaluation experiment using reaction time measurement. The results suggested that selection of the optimal enforcement form in RAA has been enabled through application of this reaction time measurement system.

Characterization of Cubic GaN Films Using An AlN/GaN Ordered Alloy on GaAs (100) by RF-MBE

High quality cubic GaN films were successfully grown on an AlN/GaN ordered alloy by RF-MBE. AlN/GaN ordered alloy is here employed instead of a AlGaN nucleation layer formed by nitridation of an AlGaAs buffer layer. Dominant cubic GaN epilayer (1.0 μm) growth was confirmed by insitu RHEED observations, AFM, TEM, PL and X-ray diffraction measurements.

Wide Bandgap II-VI Compound Superlattices Prepared by MBE and MOMBE

II–VI compound semiconductors, especially ZnS, ZnSe and ZnTe, are considered to be the promising materials for LEDs and laser diodes emitting blue light. Recently, ZnSe pn diodes have been successfully grown on GaAs by MOCVD using lithium nitride as a p-type dopant. To make a pn junction in the wide bandgap II–VI compound semiconductors, we selected a ZnSe-ZnTe superlattice structure2. We have prepared ZnSe-ZnTe strained-layer superlattices(SLS) by MBE with a modulation doping technique3. The concept of producing both p and n-type conduction using a superlattice is illustrated in Fig.1. Modulation doping of the ZnSe layers with Ga is thought to result in a n-type SLS. P-type SLS can similarly be obtained by modulation doping with Sb in the ZnTe layers. This opens up the possibility of fabricating a pn junction by using ZnSe-ZnTe SLSs. The modulation doping technique can be also applied to the ZnS(ZnSSe)- ZnTe system.