Kunishige Oe

Bio: Kunishige Oe is an academic researcher from Kyoto Institute of Technology. The author has contributed to research in topics: Molecular beam epitaxy & Semiconductor laser theory. The author has an hindex of 33, co-authored 150 publications receiving 3744 citations.

Energy band‐gap shift with elastic strain in GaxIn1−xP epitaxial layers on (001) GaAs substrates

Abstract: It is demonstrated that the energy band gap in epitaxial layers is changed by biaxial elastic strains which are produced by lattice mismatches in heterostructures. The epitaxial layers used in this work were Gax In1−xP layers grown on (001) GaAs substrates by liquid phase epitaxy. The energy band‐gap shifts were determined by comparing the photoluminescence peak energies of the as‐grown GaxIn1−xP layers with those from free‐standing layers removed from the GaAs substrates. It was experimentally found that the energy band gap shifts linearly with the elastic strain in the layer. Assuming that the lattice mismatch was accommodated only by the elastic distortion, the energy band‐gap shifts in Ga0.5In0.5P alloys were also calculated. The calculated results are 6.0 eV or 4.9×10−12 eV/dyn cm−2 per unit strain or stress, respectively, for the [100] and [010] biaxial elastic stress. These values are in quite good agreement with the experimental results.

New Semiconductor Alloy GaAs_ Bi_x Grown by Metal Organic Vapor Phase Epitaxy

Abstract: A new semiconductor alloy material, GaAs1-xBix has been created by Metal Organic Vapor Phase Epitaxial (MOVPE) growth. A low growth temperature, such as 365°C, is required to obtain the alloy. X-ray diffraction measurements of alloy layers reveal that the diffraction patterns are satisfactory. The maximum GaBi content in the GaAsBi alloy estimated from the lattice constant is around 2%, which is consistent with that estimated from secondary ion mass spectroscopy (SIMS) measurements. In a photoluminescence (PL) measurement, a single peak spectrum is observed from 10 to 300 K. The temperature variation of the PL peak energy is as small as 0.1 meV/K.

New Semiconductor Alloy GaAs1-xBix Grown by Metal Organic Vapor Phase Epitaxy

Abstract: A new semiconductor alloy material, GaAs1-xBix has been created by Metal Organic Vapor Phase Epitaxial (MOVPE) growth. A low growth temperature, such as 365°C, is required to obtain the alloy. X-ray diffraction measurements of alloy layers reveal that the diffraction patterns are satisfactory. The maximum GaBi content in the GaAsBi alloy estimated from the lattice constant is around 2%, which is consistent with that estimated from secondary ion mass spectroscopy (SIMS) measurements. In a photoluminescence (PL) measurement, a single peak spectrum is observed from 10 to 300 K. The temperature variation of the PL peak energy is as small as 0.1 meV/K.

Temperature Dependence of GaAs1-xBix Band Gap Studied by Photoreflectance Spectroscopy

Abstract: We performed photoreflectance (PR) spectroscopy in order to investigate the fundamental band gap of GaAs1-xBix alloys. The temperature dependence of the band gap energy was evaluated by analyzing of the Franz–Keldysh oscillation in the PR spectra. With increasing Bi content, the band gap energy of GaAs1-xBix alloy is reduced, which shows a large optical bowing. The temperature coefficient of the band gap decreases appreciably in alloys with increasing Bi content. For x=0.026, the temperature coefficient near room temperature is -0.15 meV/K which is 1/3 of the value for GaAs.

Characteristics of Semiconductor Alloy GaAs1-xBix.

Abstract: The characteristics of GaAs1-xBix semiconductor alloy layers grown by metalorganic vapor phase epitaxy (MOVPE) have been studied GaAs1-xBix epilayers were obtained on GaAs substrates The lattice constants of the alloy were found to increase with the addition of Bi The uniformity and the reproducibility of the solid composition of the GaAs1-xBix epilayers are good in spite of the difficulty of epitaxial growth Although layer growth was performed at a low temperature (365°C), the stability of GaAs1-xBix alloy was sufficient for device processing, which was demonstrated by annealing in an arsenic atmosphere at 560°C for 30 min The photoluminescence (PL) spectra show that the PL peak energy of the GaAs1-xBix alloy shifts to a longer wavelength with increasing Bi content The temperature dependence of the PL peak energy is much weaker than the temperature variation of the band gap of GaAs; the temperature dependence of the PL peak energy of the GaAs0974Bi0026 layer is less than one-third the temperature variation of the band gap of GaAs The results obtained in this research support the hypothesis that III–V alloy semiconductors consisting of semiconductor and semimetal components have a temperature-insensitive band gap

Lanthanide luminescence for functional materials and bio-sciences

Abstract: Recent startling interest for lanthanide luminescence is stimulated by the continuously expanding need for luminescent materials meeting the stringent requirements of telecommunication, lighting, electroluminescent devices, (bio-)analytical sensors and bio-imaging set-ups. This critical review describes the latest developments in (i) the sensitization of near-infrared luminescence, (ii) “soft” luminescent materials (liquid crystals, ionic liquids, ionogels), (iii) electroluminescent materials for organic light emitting diodes, with emphasis on white light generation, and (iv) applications in luminescent bio-sensing and bio-imaging based on time-resolved detection and multiphoton excitation (500 references).

GaAs, AlAs, and AlxGa1−xAs: Material parameters for use in research and device applications

Abstract: The Al x Ga1−x As/GaAs heterostructure system is potentially useful material for high‐speed digital, high‐frequency microwave, and electro‐optic device applications Even though the basic Al x Ga1−x As/GaAs heterostructure concepts are understood at this time, some practical device parameters in this system have been hampered by a lack of definite knowledge of many material parameters Recently, Blakemore has presented numerical and graphical information about many of the physical and electronic properties of GaAs [J S Blakemore, J Appl Phys 5 3, R123 (1982)] The purpose of this review is (i) to obtain and clarify all the various material parameters of Al x Ga1−x As alloy from a systematic point of view, and (ii) to present key properties of the material parameters for a variety of research works and device applications A complete set of material parameters are considered in this review for GaAs, AlAs, and Al x Ga1−x As alloys The model used is based on an interpolation scheme and, therefore, necessitates known values of the parameters for the related binaries (GaAs and AlAs) The material parameters and properties considered in the present review can be classified into sixteen groups: (1) lattice constant and crystal density, (2) melting point, (3) thermal expansion coefficient, (4) lattice dynamic properties, (5) lattice thermal properties, (6) electronic‐band structure, (7) external perturbation effects on the band‐gap energy, (8) effective mass, (9) deformation potential, (10) static and high‐frequency dielectric constants, (11) magnetic susceptibility, (12) piezoelectric constant, (13) Frohlich coupling parameter, (14) electron transport properties, (15) optical properties, and (16) photoelastic properties Of particular interest is the deviation of material parameters from linearity with respect to the AlAs mole fraction x Some material parameters, such as lattice constant, crystal density, thermal expansion coefficient, dielectric constant, and elastic constant, obey Vegard’s rule well Other parameters, eg, electronic‐band energy, lattice vibration (phonon) energy, Debye temperature, and impurity ionization energy, exhibit quadratic dependence upon the AlAs mole fraction However, some kinds of the material parameters, eg, lattice thermal conductivity, exhibit very strong nonlinearity with respect to x, which arises from the effects of alloy disorder It is found that the present model provides generally acceptable parameters in good agreement with the existing experimental data A detailed discussion is also given of the acceptability of such interpolated parameters from an aspect of solid‐state physics Key properties of the material parameters for use in research work and a variety of Al x Ga1−x As/GaAs device applications are also discussed in detail

PHASAR-based WDM-devices: Principles, design and applications

Abstract: Wavelength multiplexers, demultiplexers and routers based on optical phased arrays play a key role in multiwavelength telecommunication links and networks. In this paper, a detailed description of phased-array operation and design is presented and an overview is given of the most important applications.