The Experts below are selected from a list of 16278 Experts worldwide ranked by ideXlab platform
Shinichi Takagi - One of the best experts on this subject based on the ideXlab platform.
-
Mobility Enhancement techniques for ge and gesn mosfets
Journal of Semiconductors, 2021Co-Authors: Ran Cheng, Shinichi Takagi, Mitsuru Takenaka, Zhuo Chen, Sicong Yuan, Genquan Han, Rui ZhangAbstract:The performance Enhancement of conventional Si MOSFETs through device scaling is becoming increasingly difficult. The application of high Mobility channel materials is one of the most promising solutions to overcome the bottleneck. The Ge and GeSn channels attract a lot of interest as the alternative channel materials, not only because of the high carrier Mobility but also the superior compatibility with typical Si CMOS technology. In this paper, the recent progress of high Mobility Ge and GeSn MOSFETs has been investigated, providing feasible approaches to improve the performance of Ge and GeSn devices for future CMOS technologies.
-
high performance ingaas on insulator mosfets on si by novel direct wafer bonding technology applicable to large wafer size si
Symposium on VLSI Technology, 2014Co-Authors: Ryosho Nakane, Mitsuru Takenaka, Masafumi Yokoyama, Sanghyeon Kim, Yuki Ikku, Y C Kao, Shinichi TakagiAbstract:In this paper, we present first demonstration of InGaAs-on-insulator (-OI) MOSFETs with wafer size scalability up to Si wafer size of 300 mm and larger by direct wafer bonding (DWB) process using InGaAs channels grown on 4-inch Si donor substrates with III-V buffer layers instead of InP donor substrates. It is found that this DWB process can provide the high quality InGaAs thin films on Si. The fabricated InGaAs-OI MOSFETs exhibited the high electron Mobility of 1700 cm 2 /Vs and large Mobility Enhancement of 3 × against Si MOSFETs.
-
highly strained sige on insulator p channel metal oxide semiconductor field effective transistors fabricated by applying ge condensation technique to strained si on insulator substrates
Applied Physics Letters, 2011Co-Authors: Junkyo Suh, Mitsuru Takenaka, Ryosho Nakane, Noriyuki Taoka, Shinichi TakagiAbstract:High hole Mobility Enhancement of strained SiGe-on-insulator (sSGOI) p-channel metal-oxide-semiconductor field-effect transistors (pMOSFETs) has been achieved by utilizing strained-SOI (sSOI) substrates in Ge condensation. The initial tensile strain in the sSOI substrates alleviates strain relaxation during Ge condensation process, because of smaller lattice mismatch to Ge than conventional unstrained SOI substrates. In addition, generation of hole carrier concentration and degradation of bottom interface are suppressed. Mitigation in strain relaxation is shown to effectively increase strain in SGOI layers and resulting hole Mobility in the SGOI pMOSFETs in high Ge content region. The observed high Mobility Enhancement can be quantitatively explained by the combination of high Ge content and a large amount of compressive strain, through comparison of experimental data with theoretical calculations.
-
device structures and carrier transport properties of advanced cmos using high Mobility channels
Solid-state Electronics, 2007Co-Authors: Shu Nakaharai, Shinichi Takagi, Toshifumi Irisawa, Tsutomu Tezuka, K Usuda, N Sugiyama, Masato Shichijo, Ryosho Nakane, T NumataAbstract:Abstract Mobility Enhancement technologies have currently been recognized as mandatory for future scaled MOSFETs. In this paper, the recent Mobility Enhancement technologies including application of strain and new channel materials such as SiGe, Ge and III–V materials are reviewed. These carrier transport Enhancement technologies can be classified into three categories; global Enhancement techniques, local Enhancement techniques and global/local-merged techniques. We present our recent results on MOSFETs using these three types of the technologies with an emphasis on the global strained-Si/SiGe/Ge substrates and the combination with the local techniques. Finally, issues on device structures merged with III–V materials are briefly described.
-
high performance uniaxially strained sige on insulator pmosfets fabricated by lateral strain relaxation technique
IEEE Transactions on Electron Devices, 2006Co-Authors: T Numata, Toshifumi Irisawa, Tsutomu Tezuka, Koji Usuda, Norio Hirashita, Naoharu Sugiyama, Eiji Toyoda, Shinichi TakagiAbstract:Novel uniaxially strained SiGe-on-insulator (SGOI) pMOSFETs with Ge content of 20% have been successfully fabricated by utilizing lateral (uniaxial) strain-relaxation process on globally (biaxially) strained SGOI substrates. Drastic increase of drain current (80%) caused by the change of strain from biaxial to uniaxial and the Mobility Enhancement of about 100% against the control Si-on-insulator pMOSFETs are observed in SGOI pMOSFET. This high Mobility Enhancement is maintained in high vertical effective fields as well as in short-channel devices. As a result, significant ION Enhancement of 80% is demonstrated in 40-nm gate-length uniaxially strained SGOI pMOSFET
J F Gibbons - One of the best experts on this subject based on the ideXlab platform.
-
comparative study of phonon limited Mobility of two dimensional electrons in strained and unstrained si metal oxide semiconductor field effect transistors
Journal of Applied Physics, 1996Co-Authors: Shinichi Takagi, J L Hoyt, J Welser, J F GibbonsAbstract:The phonon‐limited Mobility of strained Si metal–oxide–semiconductor field‐effect transistors (MOSFETs) fabricated on a SiGe substrate is investigated through theoretical calculations including two‐dimensional quantization, and compared with the Mobility of conventional (unstrained) Si MOSFETs. In order to match both the Mobility of unstrained Si MOSFETs and the Mobility Enhancement in strained Si MOSFETs, it is necessary to increase the coupling of electrons in the two‐dimensional gas with intervalley phonons, compared to the values used in conventional models. The Mobility Enhancement associated with strain in Si is attributed to the following two factors: the suppression of intervalley phonon scattering due to the strain‐induced band splitting, and the decrease in the occupancy of the fourfold valleys which exhibit a lower Mobility due to the stronger interaction with intervalley phonons. While the decrease in the averaged conductivity mass, caused by the decrease in the occupancy of the fourfold valle...
-
electron Mobility Enhancement in strained si n type metal oxide semiconductor field effect transistors
IEEE Electron Device Letters, 1994Co-Authors: J Welser, J L Hoyt, J F GibbonsAbstract:Enhanced performance is demonstrated in n-type metal-oxide-semiconductor field-effect transistors with channel regions formed by pseudomorphic growth of strained Si on relaxed Si/sub 1/spl minus/x/Ge/sub x/. Standard MOS fabrication techniques were utilized, including thermal oxidation of the strained Si. Surface channel devices show low-field Mobility Enhancements of 80% at room temperature and 12% at 10 K, when compared to control devices fabricated in Czochralski Si. Similar Enhancements are observed in the device transconductance. In addition, buried channel devices show peak room temperature mobilities about three times that of control devices. >
Gerhard Fettweis - One of the best experts on this subject based on the ideXlab platform.
-
network massive mimo transmission over millimeter wave and terahertz bands Mobility Enhancement and blockage mitigation
IEEE Journal on Selected Areas in Communications, 2020Co-Authors: Li You, Xu Chen, Xiaohang Song, Fan Jiang, Wenjin Wang, Xiqi Gao, Gerhard FettweisAbstract:Mobility and blockage are two critical challenges in wireless transmission over millimeter-wave (mmWave) and Terahertz (THz) bands. In this paper, we investigate network massive multiple-input multiple-output (MIMO) transmission for mmWave/THz downlink in the presence of Mobility and blockage. Considering the mmWave/THz propagation characteristics, we first propose to apply per-beam synchronization for network massive MIMO to mitigate the channel Doppler and delay dispersion effects. Accordingly, we establish a transmission model. We then investigate network massive MIMO downlink transmission strategies with only the statistical channel state information (CSI) available at the base stations (BSs), formulating the strategy design as an optimization problem to maximize the network sum-rate. We show that the beam domain is favorable to perform transmission, and demonstrate that BSs can work individually when sending signals to user terminals. Based on these insights, the network massive MIMO precoding design is reduced to a network sum-rate maximization problem with respect to beam domain power allocation. By exploiting the sequential optimization method and random matrix theory, an iterative algorithm with guaranteed convergence performance is further proposed for beam domain power allocation. Numerical results reveal that the proposed network massive MIMO transmission approach with the statistical CSI can effectively alleviate the blockage effects and provide Mobility Enhancement over mmWave and THz bands.
-
network massive mimo transmission over millimeter wave and terahertz bands Mobility Enhancement and blockage mitigation
arXiv: Signal Processing, 2020Co-Authors: Li You, Xu Chen, Xiaohang Song, Fan Jiang, Wenjin Wang, Xiqi Gao, Gerhard FettweisAbstract:Mobility and blockage are two critical challenges in wireless transmission over millimeter-wave (mmWave) and Terahertz (THz) bands. In this paper, we investigate network massive multiple-input multiple-output (MIMO) transmission for mmWave/THz downlink in the presence of Mobility and blockage. Considering the mmWave/THz propagation characteristics, we first propose to apply per-beam synchronization for network massive MIMO to mitigate the channel Doppler and delay dispersion effects. Accordingly, we establish a transmission model. We then investigate network massive MIMO downlink transmission strategies with only the statistical channel state information (CSI) available at the base stations (BSs), formulating the strategy design problem as an optimization problem to maximize the network sum-rate. We show that the beam domain is favorable to perform transmission, and demonstrate that BSs can work individually when sending signals to user terminals. Based on these insights, the network massive MIMO precoding design is reduced to a network sum-rate maximization problem with respect to beam domain power allocation. By exploiting the sequential optimization method and random matrix theory, an iterative algorithm with guaranteed convergence performance is further proposed for beam domain power allocation. Numerical results reveal that the proposed network massive MIMO transmission approach with the statistical CSI can effectively alleviate the blockage effects and provide Mobility Enhancement over mmWave and THz bands.
Li You - One of the best experts on this subject based on the ideXlab platform.
-
network massive mimo transmission over millimeter wave and terahertz bands Mobility Enhancement and blockage mitigation
IEEE Journal on Selected Areas in Communications, 2020Co-Authors: Li You, Xu Chen, Xiaohang Song, Fan Jiang, Wenjin Wang, Xiqi Gao, Gerhard FettweisAbstract:Mobility and blockage are two critical challenges in wireless transmission over millimeter-wave (mmWave) and Terahertz (THz) bands. In this paper, we investigate network massive multiple-input multiple-output (MIMO) transmission for mmWave/THz downlink in the presence of Mobility and blockage. Considering the mmWave/THz propagation characteristics, we first propose to apply per-beam synchronization for network massive MIMO to mitigate the channel Doppler and delay dispersion effects. Accordingly, we establish a transmission model. We then investigate network massive MIMO downlink transmission strategies with only the statistical channel state information (CSI) available at the base stations (BSs), formulating the strategy design as an optimization problem to maximize the network sum-rate. We show that the beam domain is favorable to perform transmission, and demonstrate that BSs can work individually when sending signals to user terminals. Based on these insights, the network massive MIMO precoding design is reduced to a network sum-rate maximization problem with respect to beam domain power allocation. By exploiting the sequential optimization method and random matrix theory, an iterative algorithm with guaranteed convergence performance is further proposed for beam domain power allocation. Numerical results reveal that the proposed network massive MIMO transmission approach with the statistical CSI can effectively alleviate the blockage effects and provide Mobility Enhancement over mmWave and THz bands.
-
network massive mimo transmission over millimeter wave and terahertz bands Mobility Enhancement and blockage mitigation
arXiv: Signal Processing, 2020Co-Authors: Li You, Xu Chen, Xiaohang Song, Fan Jiang, Wenjin Wang, Xiqi Gao, Gerhard FettweisAbstract:Mobility and blockage are two critical challenges in wireless transmission over millimeter-wave (mmWave) and Terahertz (THz) bands. In this paper, we investigate network massive multiple-input multiple-output (MIMO) transmission for mmWave/THz downlink in the presence of Mobility and blockage. Considering the mmWave/THz propagation characteristics, we first propose to apply per-beam synchronization for network massive MIMO to mitigate the channel Doppler and delay dispersion effects. Accordingly, we establish a transmission model. We then investigate network massive MIMO downlink transmission strategies with only the statistical channel state information (CSI) available at the base stations (BSs), formulating the strategy design problem as an optimization problem to maximize the network sum-rate. We show that the beam domain is favorable to perform transmission, and demonstrate that BSs can work individually when sending signals to user terminals. Based on these insights, the network massive MIMO precoding design is reduced to a network sum-rate maximization problem with respect to beam domain power allocation. By exploiting the sequential optimization method and random matrix theory, an iterative algorithm with guaranteed convergence performance is further proposed for beam domain power allocation. Numerical results reveal that the proposed network massive MIMO transmission approach with the statistical CSI can effectively alleviate the blockage effects and provide Mobility Enhancement over mmWave and THz bands.
-
Network Massive MIMO Transmission Over Millimeter-Wave and Terahertz Bands: Mobility Enhancement and Blockage Mitigation
'Institute of Electrical and Electronics Engineers (IEEE)', 2020Co-Authors: Li You, Xu Chen, Song Xiaohang, Jiang Fan, Wang Wenjin, Gao Xiqi, Fettweis GerhardAbstract:Mobility and blockage are two critical challenges in wireless transmission over millimeter-wave (mmWave) and Terahertz (THz) bands. In this paper, we investigate network massive multiple-input multiple-output (MIMO) transmission for mmWave/THz downlink in the presence of Mobility and blockage. Considering the mmWave/THz propagation characteristics, we first propose to apply per-beam synchronization for network massive MIMO to mitigate the channel Doppler and delay dispersion effects. Accordingly, we establish a transmission model. We then investigate network massive MIMO downlink transmission strategies with only the statistical channel state information (CSI) available at the base stations (BSs), formulating the strategy design problem as an optimization problem to maximize the network sum-rate. We show that the beam domain is favorable to perform transmission, and demonstrate that BSs can work individually when sending signals to user terminals. Based on these insights, the network massive MIMO precoding design is reduced to a network sum-rate maximization problem with respect to beam domain power allocation. By exploiting the sequential optimization method and random matrix theory, an iterative algorithm with guaranteed convergence performance is further proposed for beam domain power allocation. Numerical results reveal that the proposed network massive MIMO transmission approach with the statistical CSI can effectively alleviate the blockage effects and provide Mobility Enhancement over mmWave and THz bands.Comment: to appear in IEEE Journal on Selected Areas in Communication
Noriyuki Taoka - One of the best experts on this subject based on the ideXlab platform.
-
electron Mobility Enhancement of extremely thin body in0 7ga0 3as on insulator metal oxide semiconductor field effect transistors on si substrates by metal oxide semiconductor interface buffer layers
Applied Physics Express, 2012Co-Authors: Sanghyeon Kim, Ryosho Nakane, Masafumi Yokoyama, Noriyuki Taoka, Ryo Iida, Sunghoon Lee, Yuji Urabe, Noriyuki Miyata, Tetsuji Yasuda, Hisashi YamadaAbstract:The electron Mobility Enhancement of extremely thin body In0.7Ga0.3As-on-insulator (-OI) metal–oxide–semiconductor field-effect transistors (MOSFETs) on Si substrates by using In0.3Ga0.7As MOS interface buffer layers was demonstrated. The MOSFETs with the InGaAs thickness of 2/5/3 nm have exhibited the electron Mobility of 2810 cm2 V-1 s-1 with an Enhancement factor of 4.2 against that of Si MOSFET. We have examined the body thickness (Tbody) dependence of the electron Mobility. It was found that a channel thickness fluctuation scattering mechanism strongly affects the Mobility in Tbody of around 10 nm and thinner. The formation of a uniform and flat InGaAs-OI wafer is required for further improvements.
-
highly strained sige on insulator p channel metal oxide semiconductor field effective transistors fabricated by applying ge condensation technique to strained si on insulator substrates
Applied Physics Letters, 2011Co-Authors: Junkyo Suh, Mitsuru Takenaka, Ryosho Nakane, Noriyuki Taoka, Shinichi TakagiAbstract:High hole Mobility Enhancement of strained SiGe-on-insulator (sSGOI) p-channel metal-oxide-semiconductor field-effect transistors (pMOSFETs) has been achieved by utilizing strained-SOI (sSOI) substrates in Ge condensation. The initial tensile strain in the sSOI substrates alleviates strain relaxation during Ge condensation process, because of smaller lattice mismatch to Ge than conventional unstrained SOI substrates. In addition, generation of hole carrier concentration and degradation of bottom interface are suppressed. Mitigation in strain relaxation is shown to effectively increase strain in SGOI layers and resulting hole Mobility in the SGOI pMOSFETs in high Ge content region. The observed high Mobility Enhancement can be quantitatively explained by the combination of high Ge content and a large amount of compressive strain, through comparison of experimental data with theoretical calculations.