A5026131803- Semiconductor Quantum Structures and Devices
- Semiconductor Lasers and Optical Devices
- Quantum Dots Synthesis And Properties
- Photonic and Optical Devices
- GaN-based semiconductor devices and materials
- Quantum and electron transport phenomena
- Strong Light-Matter Interactions
- Photorefractive and Nonlinear Optics
- Nanowire Synthesis and Applications
- Photonic Crystals and Applications
- Advanced Fiber Laser Technologies
- Semiconductor materials and devices
- Advanced Semiconductor Detectors and Materials
- Genetics and Neurodevelopmental Disorders
- Genomics and Rare Diseases
- Epigenetics and DNA Methylation
- Spectroscopy and Laser Applications
- Silicon and Solar Cell Technologies
- Schizophrenia research and treatment
- Silicon Nanostructures and Photoluminescence
- Genomic variations and chromosomal abnormalities
- Genetic Associations and Epidemiology
- ZnO doping and properties
- Near-Field Optical Microscopy
- Glycogen Storage Diseases and Myoclonus
Juntendo University
2022-2025
Juntendo University Hospital
2022
RIKEN Center for Brain Science
2021-2022
The University of Tokyo
2006-2019
Tokyo University of Social Welfare
2017-2018
Gunma University
2013-2017
Osaka University
2017
Seoul National University
2016
Sumitomo Electric Industries (Japan)
2010
Tokyo University of Science
1996-2005
The spectral response of a monolithic semiconductor quantum microcavity with wells as the active medium displays mode splitting when and optical cavity are in resonance. This effect can be seen Rabi vacuum-field quantum-well excitons, or more classically normal-mode coupled oscillators, electromagnetic field microcavity. An exciton oscillator strength 4\ifmmode\times\else\texttimes\fi{}${10}^{12}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}2}$ is deduced for 76-\AA{} wells.
Comparison of near-field and far-field photoluminescence excitation (PLE) spectra gives new insight into the carrier relaxation process in InGaAs/GaAs self-assembled quantum dots. The PLE single dots clearly show 2D-like continuum states a number sharp lines, between large zero-absorption region due to quasi-0D density 2D wetting layer absorption edge. results reveal an efficient intradot mechanism, proceeding as follows: carriers can relax easily within states, make transitions excitonic...
We report the direct deposition of strained InGaAs-dot structures with a diameter about 15 nm on GaAs surfaces by metalorganic chemical vapor growth. High resolution scanning electron micrographs show highly uniform quantum-sized dots formed Stranski–Krastanow growth mode. The sharp photoluminescence emission band buried dot indicates efficient carrier capture and homogeneous heterointerface. average size area density can be controlled accurately temperature, InGaAs thickness, respectively.
We have used femtosecond optical spectroscopy to observe directly the vacuum Rabi oscillations associated with coupled exciton-photon mode splitting in a semiconductor quantum microcavity. When microcavity is impulsively excited by coherent short pulse, time-resolved emission from cavity shows beats corresponding oscillation between and exciton modes, decay approximately twice lifetime. Interferometric pump-probe measurements clearly show evolution of polarization.
Self-alignment of InGaAs quantum dots was achieved by growing the on multiatomic steps in metalorganic chemical vapor deposition. In this technique, first GaAs epilayer with step structures along straight lines grown a vicinal substrate under appropriate growth conditions. Then, were selectively edges using strain effects. This technique results spontaneously aligned without any preprocessing prior to growth.
Successful fabrication of thin GaAs quantum wires (120–200 Å)×(200–300 Å) by a novel metal-organic chemical-vapor-deposition growth technique is reported. The were grown on V groove formed two triangular prisms which selectively SiO2 masked substrates. has very sharp corner at the bottom, results in reduction effective width wire structures. measurement photoluminescence and excitation spectra with polarization dependence indicate existence quantized state wires.
Magnetophotoluminescence spectra of GaAs quantum wires with lateral and vertical dimensions 20 10 nm, respectively, were measured up to 40 T three orthogonal magnetic field configurations. The observed photoluminescence peak shift increase applied was strongly dependent on the direction field, which directly demonstrates existence two-dimensional confinement in wires. It found that excitons anisotropically shrunk wires, anisotropic energy consistent size wire structure.
GaAs triangular-shaped quantum wires with the lateral width of ∼10 nm are fabricated by metalorganic chemical vapor selective deposition growth technique. The dimension is determined both photoluminescence (PL) measurement and a high-resolution scanning electron micrograph observation. A systematic change in size wire exhibits consistent blue shifts PL peak keeping high intensities, which demonstrates enhanced two-dimensional confinement material quality.
We report the demonstration of site-controlled InAs/GaAs quantum dots (QDs) embedded in GaAs nanowires (NWs) by selective metalorganic chemical vapor deposition. quantum-dot-in-nanowires (QD-in-NWs) with various InAs thicknesses are realized on patterned GaAs(111)B substrates form heterostructures and identified structural analyses using scanning transmission electron microscopy photoluminescence characterization. Sharp excitonic emission peaks at 10 K from single QD-in-NWs narrowest exciton...
Abstract Bipolar disorder is a severe mental illness characterized by recurrent manic and depressive episodes. To better understand its genetic architecture, we analyze ultra-rare de novo mutations in 354 trios with bipolar disorder. For germline mutations, find significant enrichment of loss-of-function constrained genes (corrected- P = 0.0410) deleterious presynaptic active zone (FDR 0.0415). An analysis integrating single-cell RNA-sequencing data identifies subset excitatory neurons...
Abstract Bipolar disorder (BD) is a global medical issue, afflicting around 1% of the population with manic and depressive episodes. Despite various genetic studies, architecture pathogenesis BD have not been fully resolved. Besides germline variants, postzygotic mosaic variants are proposed as new candidate mechanisms contributing to BD. Here, we performed extensive deep exome sequencing (DES, ~300×) validation experiments investigate roles in 235 cases (194 probands trios 41 single cases)...
We report on in situ fabrication and the photoluminescence spectra of pyramid-shaped GaAs dot structures grown (100) substrates using selective epitaxial growth by metalorganic chemical vapor deposition. The have lateral size 25 nm period 140 nm, showing a clear peak with strong intensity. In addition, energy change magnetophotoluminescence demonstrates enhancement exciton binding due to confinement.
Recent studies have shown that microRNAs (miRNAs) play a role as regulators of neurodevelopment by modulating gene expression. Altered miRNA expression has been reported in various psychiatric disorders, including schizophrenia. However, the changes profile occur during initial stage schizophrenia not fully investigated. To explore global alterations profiles may be associated with onset schizophrenia, we first profiled plasma from 17 patients first-episode and healthy controls using...
We fabricated GaAs arrowhead-shaped quantum wires utilizing both the selective growth technique and difference in stabilized crystal facet between Al0.4Ga0.6As; of layer is (111)A that Al0.4Ga0.6As (311)A. A systematic change size wire exhibits blue shifts photoluminescence peak, which due to enhancement two-dimensional confinement effect.
We investigate enhanced and inhibited spontaneous emission effects in a vertical λ-microcavity structure having two kinds of quantum wells (QWs) with the thicknesses 76 114 Å, measuring both photoluminescence intensity carrier lifetime. The Å QWs are placed at maximum nodes emitted standing wave microcavity, respectively. When mode is tuned to quantized band-gap energy (enhanced condition), PL compared case that cavity (inhibited condition). In addition, increase lifetime also observed under...
A picosecond pulse (<1.8 ps) at 8570 Å is successfully generated by a gain switching method in an optically pumped GaAs/AlGaAs multiquantum well laser with cavity length of 155 μm. This the narrowest width so far achieved semiconductor lasers without external cavity. We believe that this short generation results from enhanced differential due to two-dimensional properties carriers quantum wells.
We demonstrate a highly uniform, dense stack of In0.22Ga0.78As/GaAs quantum dot (QD) structures in single GaAs nanowire (NW). The size (and hence emission energy) individual QD is tuned by careful control the growth conditions based on diffusion model morphological evolution NWs and optical characterization. By carefully tailoring energies QD, dot-to-dot inhomogeneous broadening stacks NW can be as narrow 9.3 meV. This method provides huge advantages over traditional using strain-induced...
The aim of this study was to provide new insights into the genetics bipolar disorder (BD) by analyzing BD comorbid with anxiety disorders. Structured interviews were conducted patients and their parents. Cases classified those spectrum (AS) without. family history AS assessed. Focusing on parent-of-origin effects genomic imprinting from results, imprinted genes tested single nucleotide polymorphisms (SNPs) in identified investigated for an association transmission disequilibrium test (TDT)...
Using near-field optical microscopy, we have performed coherent excitation spectroscopy of self-assembled quantum dots (SAQDs). A pair pulses with a time delay between them allows measurement the temporal coherence carrier wave function in single dots. The observed decoherence is about 15 ps and well explained by resonant Raman scattering phonons. Furthermore, beats originating from superposition two closely spaced states been observed. This opens up possibilities mechanical control SAQDs.