Shimomura Kazuhiko

We report here on the successful transfer of thin film InP epi-layer onto Si substrate using wafer direct bonding technique, to be used as a platform of GaInAsP system growth. Our approach is promising in terms of high density integration of InP-based several functional devices on Si substrate.

Thin film InP/Si substrate was fabricated using direct wafer bonding technique. GaInAs/InP MQW layers were grown on this substrate by low pressure metalorganic vapor phase epitaxy (MOVPE) growth. Scanning electron microscope (SEM) photographs of the substrate after MOVPE growth show that the MQW layers were grown over the InP/Si substrate, and poly-crystals were observed where the Si substrate was exposed. And we have obtained almost the same photoluminescence (PL) intensity from the GaInAs/InP MQW layers on InP/Si substrate compared to those on InP substrate. According to the X-ray diffraction measurement, a slight tensile strain at the bonded interface due to the difference of thermal expansion coefficient of the InP substrate and Si substrate is observed. (C) 2013 Published by Elsevier B.V.

We have developed an ultrathin InP template with low defect density on SiO2-Si and glass substrate by employing wet etching and wafer direct bonding technique. We have demonstrated epitaxial growth on these substrates and GaInAs/InP multiple quantum well layers were grown by low pressure metal-organic vapor-phase epitaxy. Photoluminescence measurements of the layers show that they are optically active and we have obtained almost the same intensity from these substrates compared to the InP substrate. These results may be attributed to improvement of InP template quality and should provide further improvements in device performance realized on SiO2-Si and glass substrate. And, these are promising results in terms of integration of InP-based several functional optical devices on SiO2-Si and glass substrate. © 2013 WILEY-VCH Verlag GmbH &amp Co. KGaA, Weinheim.

Au-assisted growth of InAs NWs by MOVPE growth was investigated. We will discuss the NWs characteristics on GaAs and InP substrate with (111)B and (100) orientation, and on the V/III ratio during the growth. We have observed the growth direction of NWs on each substrates and confirmed that the surface diffusion have relation to the diameter of NWs. In the GaAs (111)B substrate, the diameter and length of NWs were depended on the local density of NWs. Furthermore, the tapered NWs were decreased by lowering the V/III ratio. © 2013 WILEY-VCH Verlag GmbH &amp Co. KGaA, Weinheim.

We have investigated the current injected spectrum of flat-topped LED using self-assembled Stranski-Krastanov (S-K) InAs/InP quantum dots (QDs) grown by selective area low pressure metalorganic vapor phase epitaxy and a double-capping procedure. Selective area growth using an SiO2 mask with narrow stripes was carried out to tailor a wide emission range for the QDs in sixteen arrayed waveguides. Each waveguide core contained three stacked QD layers with different QD heights and Ga content in the GaInAs buffer layer. We have measured the spectrum change of current injection, and have estimated the intensity variation in each QDs layer. By increasing the FCL thickness of three QDs layers, output intensity of each layer has become equal, and we have obtained more than 500 nm spectrum width with flat-topped spectrum shape. (C) 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

We have developed an ultrathin InP template with low defect density on SiO2-Si and glass substrate by employing wet etching and wafer direct bonding technique. We have demonstrated epitaxial growth on these substrates and GaInAs/InP multiple quantum well layers were grown by low pressure metal-organic vapor-phase epitaxy. Photoluminescence measurements of the layers show that they are optically active and we have obtained almost the same intensity from these substrates compared to the InP substrate. These results may be attributed to improvement of InP template quality and should provide further improvements in device performance realized on SiO2-Si and glass substrate. And, these are promising results in terms of integration of InP-based several functional optical devices on SiO2-Si and glass substrate. (C) 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

InP/Si substrate has been fabricated by employing wet-etching and wafer direct bonding technique. The surface of the InP/Si substrate was very smooth and no strain was observed. On top of the substrate, InAs/InP quantum dots (QDs) have been monolithically grown using metal organic vapor phase epitaxy (MOVPE). According to photo-luminescence (PL) measurement, almost the same intensity, peak wavelength and full width half of maximum (FWHM) have been observed compared to QDs on InP substrate. © 2013 IEEE.

We have obtained the wide energy level control of InAs QDs structure where the PL peak wavelength were ranged from 1200nm to 1800nm. Stranski - Krastanov InAs QDs were grown by low pressure all metal-organic source MOVPE. We have controlled the InAs QDs energy level by changing the buffer layer composition under the QDs and the height using double-capping procedure and also supply amount of QDs.

An ultrathin InP template with extremely low defect density was realized on Si substrate using wet etching and wafer direct bonding technique. On top of the InP/Si substrate, asymmetric SiO2 mask pattern on one side of the arrayed waveguides was prepared and selective metal-organic vapor-phase epitaxy (MOVPE) growth has been demonstrated. According to the cross-sectional scanning electron micrograph (SEM) images, gradually varied height of GaInAs/InP multiple quantum well (MQW) structures were realized on the substrate and photoluminescence (PL) measurement showed different band-gaps of the MQW structures. Our approach is of importance to control the in-plane band-gap energy for the integration of InP-based various functional devices on Si substrate.

Flat-topped emission with a spectral width greater than 500 nm was obtained from self-assembled Stranski-Krastanov (SK) InAs/InP quantum dots (QDs) grown by selective area low-pressure metal organic vapor phase epitaxy using a double-capping procedure. Selective area growth using an SiO2 mask with narrow stripes was carried out to tailor a wide emission range for the QDs in sixteen arrayed waveguides. Each waveguide core contained three stacked QD layers with different QD heights and Ga content in the GaInAs buffer layer. An investigation was carried out into the optimum Ga content and QD height for increasing the emission intensity and obtaining equal intensity from each QD layer. (C) 2012 The Japan Society of Applied Physics

Wavelength demultiplexed light switching is numerically calculated in the variable index arrayed waveguide. Wavelength demultiplexed light is switched in 4 output ports by changing the refractive index of variable index arrayed waveguide with 16 array waveguides. In the calculation, the phase differences in each arrayed waveguide, and the diffraction in the star coupler are considered. In 4 output ports switching, numerically calculated the refractive index changes of 16 array waveguides are numerically calculated to obtain the 24 switching pattern, and also calculated the crosstalk of each switching.

We have demonstrated switching characteristics in a wavelength switch based on multiple GaInAs/InP quantum wells. It consisted of straight arrayed waveguides with a linearly varying refractive index distribution. The refractive index can be changed via the thermo-optic (TO) effect. Using a Ti/Au thin-film heater to generate the TO effect, we realized four-port switching at four demultiplexed wavelengths. In addition, by changing the structure of the heater from rectangular to triangular, the power consumption for four-port switching was reduced by half.

We investigate broadband luminescence LED using InAs quantum dots array waveguides structure. Quantum dots heights and composition of buffer layer be controled by selective MOVPE growth and double cap procedure. Change of energy level with each change in layer, we conduct broadband luminescence. This time, we analyzed 3 layer LED's spectrum.

More than 400nm broadband luminescence was obtained from 3 layered InAs/InP QDs array waveguides. InAs QDs were grown by Stranski-Krastanov grown mode using selective MOVPE growth and double cap procedure. The selective MOVPE was performed using 16 stripe mask array with a wide mask at one side of the array. The heights of the QDs were controlled vertically by changing the first-cap layer thickness during the double-cap procedure. Furthermore, we have tried to control the emission energy of QDs by changing the Ga composition of Ga xIn 1-xAs buffer layer under the QDs. By using these techniques, we have fabricated the broadband emission devices. © 2012 WILEY-VCH Verlag GmbH &amp Co. KGaA, Weinheim.

More than 400nm broadband luminescence was obtained from 3 layered InAs/InP QDs array waveguides. InAs QDs were grown by Stranski-Krastanov grown mode using selective MOVPE growth and double cap procedure. The selective MOVPE was performed using 16 stripe mask array with a wide mask at one side of the array. The heights of the QDs were controlled vertically by changing the first-cap layer thickness during the double-cap procedure. Furthermore, we have tried to control the emission energy of QDs by changing the Ga composition of GaxIn1-xAs buffer layer under the QDs. By using these techniques, we have fabricated the broadband emission devices. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

A novel wavelength demutiplexer and wavelength switch using arrayed waveguide with linearly varying refractive index distribution by MOVPE selective area growth has been proposed. The thickness of the each waveguide in the array has changed gradually. We have already demonstrated the switching characteristics in GaInAs/InP MQW arrayed waveguides devices by thermo-optic effect. This time, we have designed a triangular heater newly, and achieved the reduction of the consumption power for four-port switching with demultiplexed 4 wavelengths light.

Broadband spectrum emission was obtained for self-assembled Stranski-Krastanov (S-K) InAs/InP quantum dots (QDs) grown by selective area low pressure metalorganic vapor phase epitaxy (MOVPE) using the double-cap procedure. Selective area growth using a SiO(2) narrow stripe mask array pattern was carried out to control and widen the emission wavelength range of the QDs in 16 stripe mask array waveguides. The height of the QDs in the multi stacked QD layers was changed using the double-cap procedure, and the strain was controlled by changing the composition of the GaInAs buffer layer under the QDs, which resulted in the broadband spectrum emission of this structure. (C) 2010 Elsevier B.V. All rights reserved.

A novel wavelength demutiplexer and wavelength selective switch using arrayed waveguide with linearly varying refractive index distribution by MOVPE selective area growth has been proposed. By placing the asymmetric width of SiO_2 mask pattern on both sides of the arrayed waveguide, the thickness of the each waveguide in the array has changed gradually. A wavelength demultiplexer using arrayed waveguides in which refractive index varies linearly across the devices was investigated and successful fabrication of GalnAs/InP MQW arrayed waveguide devices was achieved. This time, we have obtained the structural dependence on the performance of wavelength demultiplexing and switching in the variable refractive index waveguide array which has Rowland circle structure slab waveguide using FORTRAN simulation.

InAs/InP QDs broadband LED more than 450 nm spectrum width was successfully demonstrated. The broadband spectrum was obtained from the height controlled double-cap procedure and strain controlled buffer layer fabricated by the selective MOVPE technique.

We have demonstrated a carrier-injection-type wavelength switch composed of the straight waveguide array using GaInAs/InP MQW with linearly varying refractive index distribution fabricated by selective MOVPE.

Wavelength switching in the index-varied array waveguide is calculated. The device consists of waveguide array in which the refractive index varies gradually across the array and star coupler. In the calculation, the phase differences in each array waveguide, and the diffraction in the star coupler are considered. Refractive index distribution of the array waveguide for wavelength demultiplexing, and index change for switching are obtained.

We have demonstrated wavelength selective switching in the variable index arrayed waveguides using Ti/Au thin film.

Semiconductor self-assembled quantum dots (QDs) that have zero-dimensional carrier confinement structure are predicted to have unique physical properties. And these QDs are expected to increase the performance of various semiconductor optical devices such as laser or LED. By using the semiconductor quantum well structure, only one dimension of the height can be controlled the quantum energy level, on the other hand, in the QDs structure, the three-dimensional control of the energy level is possible, and we can obtain the more wide wavelength control. For this reason, The wide wavelength emission source can be applied, such as very wideband wavelength division multiplex (WDM) system, including the 1.55μm optical telecommunication wavelength, the environmental gas detecting in the longer wavelength near the 2.0μm,and the light source for optical coherence tomography. In this study, we show the wideband wavelength electro luminescence (EL) more than 400nm of quantum dot LED using selective MOVPE growth and double-cap procedure.

A novel wavelength demutiplexer and wavelength selective switch using arrayed waveguide with linearly varying refractive index distribution by MOVPE selective area growth has been proposed. By placing the asymmetric width of SiO_2 mask pattern on both sides of the arrayed waveguide, the thickness of the each waveguide in the array has changed gradually. A wavelength demultiplexer using arrayed waveguides in which refractive index varies linearly across the devices was investigated and successful fabrication of GaInAs/InP MQW arrayed waveguide devices was achieved. This time, we have obtained the structural dependence on the performance of wavelength demultiplexing in the variable refractive index waveguide array using BPM simulation, and we have experimentally examined the change of output port intensity by carrier injection in this device.

A novel wavelength demutiplexer and wavelength selective switch using arrayed waveguide with linearly varying refractive index distribution by MOVPE selective area growth has been proposed. By placing the asymmetric width of SiO_2 mask pattern on both sides of the arrayed waveguide, the thickness of the each waveguide in the array has changed gradually. A wavelength demultiplexer using arrayed waveguides in which refractive index varies linearly across the devices was investigated and successful fabrication of GaInAs/InP MQW arrayed waveguide devices was achieved. This time, we report that four wavelength lights were switched and demultiplexed between the four output ports in the wavelength selective switch using GaInAs/InP MQW variable index arrayed waveguide by thermo-optic (TO) effect.

Wavelength selective switch using GaInAs/InP MQW variable index arrayed waveguides have successfully demonstrated. The demultiplexed wavelength light could be exchanged the output ports by changing the refractive index of arrayed waveguides by using thermo-optic effect. (C) 2009 Optical Society of America

More than 400nm spectrum width LED was obtained in the In As QDs array waveguide using height changed QDs during double-cap procedure and strain controlled buffer in 3 layered QDs.

Four wavelength switching was successfully demonstrated in the wavelength selective switch using GaInAs/InP MQW variable index arrayed waveguide by thermo-optic (TO) effect. Four wavelength lights were switched and demultiplexed between the four output ports.

We have obtained the structual dependence on the performance of wavelength demultiplexing and switching in the variable refractive-index waveguide array using BPM simulation, and we have experimentally examined the improvement of crosstalk in this device.

GaxIn1-xAs cap layer dependence on self-assembled Stranski-Krastanov (S-K) InAs quantum dots (QDs) was Successfully demonstrated using a double-cap procedure and metalorganic vapor phase epitaxy (MOVPE) selective area growth. Selective area growth with a narrow stripe SiO2 mask array pattern was used to control and widen the emission wavelength range of the QDs in a 16-stripe mask array waveguide, and the double-cap procedure was used to improve the Uniformity of the QD height. Growth of a 5-layer stacked InAs QD structure was successfully demonstrated using these methods with a Ga0.75In0.25As cap layer. (C) 2008 Elsevier B.V. All rights reserved.

Wideband wavelength electroluminescence (EL) more than 400 nm was obtained in self-assembled Stranski-Krastanov (S-K) InAs/InP quantum dots (QDs) grown by selective area low-pressure metalorganic vapor-phase epitaxy (MOVPE). We used two techniques to control the EL peak spectrum in order to obtain the wideband emission spectrum of the device. One is selective area growth using a SiO(2) narrow 16-stripe mask array pattern, and the other is a double-cap procedure in the growth of the QDs layer to change the height of QDs layer by layer. (C) 2008 Elsevier B.V. All rights reserved.

A growth technique for wide emission wavelength quantum dots (QDs) via the Stranski-Krastanov (S-K) growth mode using a double-cap procedure and metal-organic vapor phase epitaxy (MOVPE) selective area growth is proposed. By using the double-cap procedure, we have improved the uniformity of the QDs height. Selective area growth by low-pressure MOVPE using a SiO(2) narrow stripe mask array pattern was carried for controlling and widening the emission wavelength range of the QDs in 16 stripe mask array waveguides. We have successfully demonstrated QD characteristics under various growth conditions, and have realized 120 nm emission wavelength range in 16 array, five layer InAs QD waveguides.