The Experts below are selected from a list of 86883 Experts worldwide ranked by ideXlab platform
Takaaki Kakitsuka - One of the best experts on this subject based on the ideXlab platform.
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membrane distributed reflector laser integrated with Siox based spot Size converter on Si Substrate
Optics Express, 2016Co-Authors: Hidetaka Nishi, Tsuyoshi Yamamoto, Takuro Fujii, Koji Takeda, Koichi Hasebe, Takaaki Kakitsuka, Tai Tsuchizawa, Koji Yamada, Shinji MatsuoAbstract:We demonstrate monolithic integration of a 50-μm-long-cavity membrane distributed-reflector laser with a spot-Size converter, conSisting of a tapered InP wire waveguide and an SiOx waveguide, on SiO2/Si Substrate. The device exhibits 9.4-GHz/mA0.5 modulation efficiency with a 2.2-dB fiber coupling loss. We demonstrate 25.8-Gbit/s direct modulation with a bias current of 2.5 mA, resulting in a low energy cost of 132 fJ/bit.
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epitaxial growth of inp to bury directly bonded thin active layer on Sio2 Si Substrate for fabricating distributed feedback lasers on Silicon
Iet Optoelectronics, 2015Co-Authors: Takuro Fujii, Koji Takeda, Koichi Hasebe, Takaaki Kakitsuka, Tomonari Sato, Shinji MatsuoAbstract:The authors have developed a new heterogeneous-integration method for fabricating semiconductor lasers with high modulation efficiency on Si Substrates. The method employs the direct bonding of an InP-based active layer to the SiO2 layer of a thermally oxidised Si Substrate (SiO2/Si Substrate), followed by the epitaxial growth of InP to form a buried heterostructure (BH). By uSing the InP membrane, the authors realise epitaxial growth of an InP on the InP membrane directly bonded to Si without crystal quality degradation. Both a theoretical estimation and photoluminescence measurements revealed that the total laser thickness must be less than the critical thickness determined by the applied thermal strain. The authors confirmed that the crystal quality of the BH is comparable to that fabricated on an InP Substrate when uSing a 250-nm-thick InP-based membrane. A distributed feedback laser fabricated on a SiO2/Si Substrate exhibited continuous-wave operation up to 100°C and was directly modulated by a 40 Gbit/s non-return-to-zero Signal with a bias current of 15 mA. These results indicate that epitaxial growth uSing a directly bonded InP-based active layer on a SiO2/Si Substrate allows us to achieve lasers with high modulation efficiency and to use a large-scale Si wafer as a fabrication platform, resulting in low-cost fabrication.
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directly modulated dfb laser on Sio _ bf 2 Si Substrate for datacenter networks
Journal of Lightwave Technology, 2015Co-Authors: Shinji Matsuo, Takuro Fujii, Koji Takeda, Koichi Hasebe, Tomonari Sato, Takaaki KakitsukaAbstract:Reducing the operating energy of a distributed feedback (DFB) laser is a critical issue if we are to use the device as a directly modulated light source employing wavelength diviSion multiplexing technologies in short-distance datacom networks. A membrane buried heterostructure (BH) DFB laser on a SiO2 layer is one candidate for reducing the operating energy because it provides a strong carrier and optical confinement in the active region. For low-cost fabrication, we have proposed and developed a fabrication procedure that employs the buried growth of an InP layer by uSing a directly bonded InP-based active layer on a SiO2/Si Substrate, which enables us to use a large-scale Si wafer. To overcome the problem of the difference between the thermal expanSion coefficients of Si, SiO2, and InP, we have used a thin active layer (∼250 nm) on a SiO2/Si Substrate as a template for the epitaxial growth of a III–V compound semiconductor. A lateral current injection structure is essential for fabricating a device with a 250-nm-thick template. Our fabricated DFB laser with a 73-μm cavity length exhibits a threshold current of 0.9 mA for continuous operation at room temperature and achieves laSing at up to 100 °C. We have also demonstrated 171-fJ/bit operation with a 25.8-Gb/s NRZ Signal. These results indicate that the BH DFB laser on a SiO2/Si Substrate is highly suitable for use as a transmitter for datacom applications.
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directly modulated buried heterostructure dfb laser on Sio Si Substrate fabricated by regrowth of inp uSing bonded active layer
Optics Express, 2014Co-Authors: Shinji Matsuo, Takuro Fujii, Koji Takeda, Koichi Hasebe, Tomonari Sato, Takaaki KakitsukaAbstract:We describe the growth of InP layer uSing an ultrathin III-V active layer that is directly bonded to SiO₂/Si Substrate to fabricate a buried heterostructure (BH) laser. USing a 250-nm-thick bonded active layer, we succeeded in fabricating a BH distributed feedback (DFB) laser on SiO₂/Si Substrate. The use of a lateral current injection structure is important for forming a p-i-n junction uSing bonded thin film. The fabricated DFB laser is directly modulated by a 25.8-Gbit/s NRZ Signal at 50°C. These results indicate that our fabrication method is a promiSing way to fabricate high-efficiency lasers at a low cost.
Eugene A Fitzgerald - One of the best experts on this subject based on the ideXlab platform.
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integration of gaas gan and Si cmos on a common 200 mm Si Substrate through multilayer transfer process
Applied Physics Express, 2016Co-Authors: Li Zhang, Eugene A Fitzgerald, David KohenAbstract:The integration of III–V semiconductors (e.g., GaAs and GaN) and Silicon-on-insulator (SOI)-CMOS on a 200 mm Si Substrate is demonstrated. The SOI-CMOS donor wafer is temporarily bonded on a Si handle wafer and thinned down. A second GaAs/Ge/Si Substrate is then bonded to the SOI-CMOS-containing handle wafer. After that, the Si from the GaAs/Ge/Si Substrate is removed. The GaN/Si Substrate is then bonded to the SOI–GaAs/Ge-containing handle wafer. Finally, the handle wafer is released to realize the SOI–GaAs/Ge/GaN/Si hybrid structure on a Si Substrate. By this method, the functionalities of the materials used can be combined on a Single Si platform.
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study of surface microstructure origin and evolution for gaas grown on ge Si1 xgex Si Substrate
Journal of Physics D, 2009Co-Authors: S F Yoon, Eugene A Fitzgerald, Kah Pin Chen, H Tanoto, K L Lew, Carl L DohrmanAbstract:The origin and evolution of surface microstructures in the GaAs layer grown on the Ge/Si1−xGex/Si Substrate were studied. The characteristic surface microstructures are formed in pairs. By correlating the results from atomic force microscopy and cross-sectional transmisSion electron microscopy characterization, these paired surface microstructures are identified as { 111 } stacking faults that propagate at 54 ◦ with respect to the Substrate surface. The stacking faults originate from the Single-stepped GaAs/Ge heterointerface, as a consequence of in Situ annealing of the Ge surface. The surface microstructure denSity becomes lower and the mean lateral Size larger when the GaAs thickness is increased from 0.54 to 1.11 µm. (Some figures in this article are in colour only in the electronic verSion)
Nobuhiko Sawaki - One of the best experts on this subject based on the ideXlab platform.
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catalyst free mbe vls growth of gaas nanowires on 111 Si Substrate
Physica Status Solidi (c), 2009Co-Authors: Jihyun Paek, T Nishiwaki, Masahito Yamaguchi, Nobuhiko SawakiAbstract:The behaviour of catalyst free GaAs nanowire growth is investigated on (111)Si Substrate by molecular beam epitaxy under different Ga and As fluxes. It is found that the diameter of nanowire is increased by increaSing the Ga flux, while it is decreased by increaSing the As flux. The growth rate along the wire axis is enhanced by increaSing the As flux under a constant Ga flux. Moreover, the Ga droplet at the top disappears by the growth interruption and the growth along the wire axis is strictly prohibited. By adopting the last result, the growth of GaAs/AlGaAs core-shell structure is attempted. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
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al doping in 1 101 gan films grown on patterned 001 Si Substrate
Journal of Applied Physics, 2007Co-Authors: Toshiki Hikosaka, Masahito Yamaguchi, Yoshio Honda, Nobuhiko SawakiAbstract:The effect of Al doping on crystalline and optical properties of semipolar (1−101)GaN was investigated. The samples were grown on a patterned (001)Si Substrate by selective metal-organic vapor phase epitaxy. The x-ray analyses showed that the strain in the (1−101)GaN layer is reduced substantially by the Al doping. Moreover, the cathode-luminescence (CL) intenSity of the band edge emisSion band was enhanced and the linewidth became narrow. The CL images showed the reduction of dislocation denSity. These results show that the small amount of Al atoms in GaN improves the crystalline and optical properties. The results are attributed to the dislocation pinning and solution hardening effect due to Al atoms.
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defect structure in selective area growth gan pyramid on 111 Si Substrate
Applied Physics Letters, 2000Co-Authors: Shigeyasu Tanaka, Nobuhiko Sawaki, Yasutoshi Kawaguchi, Michio Hibino, Kazumasa HiramatsuAbstract:A GaN pyramid grown selectively on a (111)Si Substrate with a patterned dot structure of a SiO2 mask, by metalorganic vapor phase epitaxy uSing AlGaN as an intermediate layer, was characterized by transmisSion electron microscopy. The dot pattern has an array of 5.0-μm-diameter window openings with a 10 μm period. The denSity of threading dislocations observed in the window region decreased gradually with increaSing distance from the interface. This was mainly due to the dislocation reaction and bending of threading dislocations for the first 2 μm region from the interface and for the upper region, respectively. Dominantly observed defects in the lateral-growth part were dislocations parallel to the interface. An amorphous layer was formed at the interface in the window region. Nitride particles were observed at the interface in the mask region.
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growth of Single crystalline gan film on Si Substrate uSing 3c Sic as an intermediate layer
Journal of Crystal Growth, 1991Co-Authors: Tetsuya Takeuchi, Hiroshi Amano, Kazumasa Hiramatsu, Nobuhiko Sawaki, Isamu AkasakiAbstract:MOVPE Growth of GaN films on Si (111) Substrates has been studied. Thin 3C-SiC is found to be an effective intermediate layer for growth of Single crystalline GaN films with flat surfaces. Cathodoluminescence measurements show only strong near band-edge emisSion at RT from GaN films on Si Substrates uSing a 3C-SiC intermediate layer. The epitaxial relationship between the GaN film and a Si Substrate covered with a 3C-SiC layer is as follows: (0001)GaN|(111)Si and [1120]GaN|[110]Si
Kazumasa Hiramatsu - One of the best experts on this subject based on the ideXlab platform.
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crack free gan grown by uSing maskless epitaxial lateral overgrowth on Si Substrate with thin Sic intermediate layer
Physica Status Solidi (a), 2014Co-Authors: Hao Fang, Kazumasa Hiramatsu, M Katagiri, Hideto Miyake, Hidehiko Oku, Hidetoshi Asamura, Keisuke KawamuraAbstract:With 100-nm-thick 3C-SiC intermediate layer, GaN layer of relative high quality was obtained on Si Substrate by uSing a maskless epitaxial lateral overgrowth (ELO). The three-dimenSional growth of maskless ELO process was investigated with wafer reflectance collected during growth. Low temperature cathodoluminescence observation confirmed the improvement of the GaN quality by ELO. An AlN interlayer was used to prevent crack of the GaN epilayer. As a result, the as-grown GaN layer shows a crack-free surface with long atomic steps. The threading dislocation denSity is lower than 1 × 109 cm−2 in GaN layer underneath AlN interlayer.
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defect structure in selective area growth gan pyramid on 111 Si Substrate
Applied Physics Letters, 2000Co-Authors: Shigeyasu Tanaka, Nobuhiko Sawaki, Yasutoshi Kawaguchi, Michio Hibino, Kazumasa HiramatsuAbstract:A GaN pyramid grown selectively on a (111)Si Substrate with a patterned dot structure of a SiO2 mask, by metalorganic vapor phase epitaxy uSing AlGaN as an intermediate layer, was characterized by transmisSion electron microscopy. The dot pattern has an array of 5.0-μm-diameter window openings with a 10 μm period. The denSity of threading dislocations observed in the window region decreased gradually with increaSing distance from the interface. This was mainly due to the dislocation reaction and bending of threading dislocations for the first 2 μm region from the interface and for the upper region, respectively. Dominantly observed defects in the lateral-growth part were dislocations parallel to the interface. An amorphous layer was formed at the interface in the window region. Nitride particles were observed at the interface in the mask region.
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growth of Single crystalline gan film on Si Substrate uSing 3c Sic as an intermediate layer
Journal of Crystal Growth, 1991Co-Authors: Tetsuya Takeuchi, Hiroshi Amano, Kazumasa Hiramatsu, Nobuhiko Sawaki, Isamu AkasakiAbstract:MOVPE Growth of GaN films on Si (111) Substrates has been studied. Thin 3C-SiC is found to be an effective intermediate layer for growth of Single crystalline GaN films with flat surfaces. Cathodoluminescence measurements show only strong near band-edge emisSion at RT from GaN films on Si Substrates uSing a 3C-SiC intermediate layer. The epitaxial relationship between the GaN film and a Si Substrate covered with a 3C-SiC layer is as follows: (0001)GaN|(111)Si and [1120]GaN|[110]Si
Shinji Matsuo - One of the best experts on this subject based on the ideXlab platform.
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membrane distributed reflector laser integrated with Siox based spot Size converter on Si Substrate
Optics Express, 2016Co-Authors: Hidetaka Nishi, Tsuyoshi Yamamoto, Takuro Fujii, Koji Takeda, Koichi Hasebe, Takaaki Kakitsuka, Tai Tsuchizawa, Koji Yamada, Shinji MatsuoAbstract:We demonstrate monolithic integration of a 50-μm-long-cavity membrane distributed-reflector laser with a spot-Size converter, conSisting of a tapered InP wire waveguide and an SiOx waveguide, on SiO2/Si Substrate. The device exhibits 9.4-GHz/mA0.5 modulation efficiency with a 2.2-dB fiber coupling loss. We demonstrate 25.8-Gbit/s direct modulation with a bias current of 2.5 mA, resulting in a low energy cost of 132 fJ/bit.
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epitaxial growth of inp to bury directly bonded thin active layer on Sio2 Si Substrate for fabricating distributed feedback lasers on Silicon
Iet Optoelectronics, 2015Co-Authors: Takuro Fujii, Koji Takeda, Koichi Hasebe, Takaaki Kakitsuka, Tomonari Sato, Shinji MatsuoAbstract:The authors have developed a new heterogeneous-integration method for fabricating semiconductor lasers with high modulation efficiency on Si Substrates. The method employs the direct bonding of an InP-based active layer to the SiO2 layer of a thermally oxidised Si Substrate (SiO2/Si Substrate), followed by the epitaxial growth of InP to form a buried heterostructure (BH). By uSing the InP membrane, the authors realise epitaxial growth of an InP on the InP membrane directly bonded to Si without crystal quality degradation. Both a theoretical estimation and photoluminescence measurements revealed that the total laser thickness must be less than the critical thickness determined by the applied thermal strain. The authors confirmed that the crystal quality of the BH is comparable to that fabricated on an InP Substrate when uSing a 250-nm-thick InP-based membrane. A distributed feedback laser fabricated on a SiO2/Si Substrate exhibited continuous-wave operation up to 100°C and was directly modulated by a 40 Gbit/s non-return-to-zero Signal with a bias current of 15 mA. These results indicate that epitaxial growth uSing a directly bonded InP-based active layer on a SiO2/Si Substrate allows us to achieve lasers with high modulation efficiency and to use a large-scale Si wafer as a fabrication platform, resulting in low-cost fabrication.
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directly modulated dfb laser on Sio _ bf 2 Si Substrate for datacenter networks
Journal of Lightwave Technology, 2015Co-Authors: Shinji Matsuo, Takuro Fujii, Koji Takeda, Koichi Hasebe, Tomonari Sato, Takaaki KakitsukaAbstract:Reducing the operating energy of a distributed feedback (DFB) laser is a critical issue if we are to use the device as a directly modulated light source employing wavelength diviSion multiplexing technologies in short-distance datacom networks. A membrane buried heterostructure (BH) DFB laser on a SiO2 layer is one candidate for reducing the operating energy because it provides a strong carrier and optical confinement in the active region. For low-cost fabrication, we have proposed and developed a fabrication procedure that employs the buried growth of an InP layer by uSing a directly bonded InP-based active layer on a SiO2/Si Substrate, which enables us to use a large-scale Si wafer. To overcome the problem of the difference between the thermal expanSion coefficients of Si, SiO2, and InP, we have used a thin active layer (∼250 nm) on a SiO2/Si Substrate as a template for the epitaxial growth of a III–V compound semiconductor. A lateral current injection structure is essential for fabricating a device with a 250-nm-thick template. Our fabricated DFB laser with a 73-μm cavity length exhibits a threshold current of 0.9 mA for continuous operation at room temperature and achieves laSing at up to 100 °C. We have also demonstrated 171-fJ/bit operation with a 25.8-Gb/s NRZ Signal. These results indicate that the BH DFB laser on a SiO2/Si Substrate is highly suitable for use as a transmitter for datacom applications.
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directly modulated buried heterostructure dfb laser on Sio Si Substrate fabricated by regrowth of inp uSing bonded active layer
Optics Express, 2014Co-Authors: Shinji Matsuo, Takuro Fujii, Koji Takeda, Koichi Hasebe, Tomonari Sato, Takaaki KakitsukaAbstract:We describe the growth of InP layer uSing an ultrathin III-V active layer that is directly bonded to SiO₂/Si Substrate to fabricate a buried heterostructure (BH) laser. USing a 250-nm-thick bonded active layer, we succeeded in fabricating a BH distributed feedback (DFB) laser on SiO₂/Si Substrate. The use of a lateral current injection structure is important for forming a p-i-n junction uSing bonded thin film. The fabricated DFB laser is directly modulated by a 25.8-Gbit/s NRZ Signal at 50°C. These results indicate that our fabrication method is a promiSing way to fabricate high-efficiency lasers at a low cost.
