Article
Physics, Applied
Tomotaka Hosotani, Akira Satou, Taiichi Otsuji
Summary: This study reports on terahertz emission from a DC-current-driven dual-grating-gate high-electron-mobility transistor in a 2D channel, showing distinctive radiation spectra beyond black-body emission. The results suggest the occurrence of plasmonic boom instability stimulated by the DC current flow.
APPLIED PHYSICS EXPRESS
(2021)
Article
Physics, Multidisciplinary
Wen-Lu Yang, Lin-An Yang, Fei-Xiang Shen, Hao Zou, Yang Li, Xiao-Hua Ma, Yue Hao
Summary: A GaN-based HEMT with p-GaN island buried layer is proposed for terahertz applications. The redistribution of the electric field in the gate-drain channel region promotes the formation of electronic domains in the 2DEG channel. The simulation results show that the HEMT with a PIBL structure can generate stable oscillations up to 344 GHz-400 GHz.
Article
Engineering, Electrical & Electronic
Wan-Soo Park, Hyeon-Bhin Jo, Hyo-Jin Kim, Su-Min Choi, Ji-Hoon Yoo, Hyeon-Seok Jeong, Sethu George, Ji-Min Baek, In-Geun Lee, Tae-Woo Kim, Sang-Kuk Kim, Jacob Yun, Ted Kim, Takuya Tsutsumi, Hiroki Sugiyama, Hideaki Matsuzaki, Jae-Hak Lee, Dae-Hyun Kim
Summary: This study presents a systematic investigation on the gate length scaling behavior and the impact of side-recess spacing on the characteristics of In0.8Ga0.2As quantum-well high-electron-mobility transistors. It aims to understand the scaling limit of maximum oscillation frequency and demonstrate the potential of terahertz devices.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Article
Engineering, Electrical & Electronic
Akhil Ranjan, Ravikiran Lingaparthi, Nethaji Dharmarasu, K. Radhakrishnan
Summary: This study establishes a theoretical relationship between the properties of a two-dimensional electron gas (2DEG) in AlGaN/GaN HEMT heterostructure and various gas-sensing characteristics. It is proposed that using a thinner barrier layer in the heterostructure can lead to lower detection limits, higher sensing response, and faster response time. Experimental results confirm these analytical findings by comparing a thin-barrier gas sensor with a thick-barrier gas sensor.
IEEE SENSORS JOURNAL
(2022)
Article
Engineering, Electrical & Electronic
Ankit Soni, Mayank Shrivastava
Summary: This study investigated the impact of various charge sources on the electric field distribution and breakdown mechanism of HEMTs, revealing strong correlations between different charges and breakdown voltage. Insights were developed to explain the dependence of HEMT breakdown on surface states, polarization charge, and buffer traps, aiding in the design of efficient surface passivation schemes.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2021)
Article
Chemistry, Analytical
Idriss Abid, Youssef Hamdaoui, Jash Mehta, Joff Derluyn, Farid Medjdoub
Summary: We report on the fabrication and electrical characterization of AlGaN/GaN normally off transistors on silicon designed for high-voltage operation. The normally off configuration was achieved with a p-gallium nitride (p-GaN) cap layer below the gate, enabling a positive threshold voltage higher than +1 V. The buffer structure was based on AlN/GaN superlattices (SLs), delivering a vertical breakdown voltage close to 1.5 kV with a low leakage current all the way to 1200 V.
Article
Materials Science, Multidisciplinary
V. Hemaja, D. K. Panda
Summary: An n-polar GaN MIS-HEMT based biosensor is proposed for label-free detection of various bio-molecules by immobilizing the analytes in the underlap region to alter the electrostatic properties of the device, resulting in a significant increase in drain current and output conductance with the addition of different biomolecules in the nanocavity, with a maximum shift in threshold voltage observed for uricase due to its low dielectric constant.
ECS JOURNAL OF SOLID STATE SCIENCE AND TECHNOLOGY
(2021)
Article
Engineering, Electrical & Electronic
Nipun Sharma, Arun Kumar Sakthivel, Subbiah Alwarrapan, Ankur Gupta, Ahmed S. Razeen, Dharmraj Subhash Kotekar Patil, Sudhiranjan Tripathy, Mahesh Kumar
Summary: The quick and easy monitoring of heavy metals in drinking water is of utmost importance due to their harmful effects on human health. In this study, a GaN-based HEMT sensor was fabricated and used to detect trace Pb2+ ions in water. The sensor showed a sensitivity of 0.46 mu A/ppb with a detection limit of 0.32 ppb, which is below international standards. Real-time measurements on lake water were also performed using this sensor, demonstrating its fast and ultrasensitive detection capabilities. This work serves as a proof-of-concept for the development of heavy metal ion sensors.
IEEE SENSORS JOURNAL
(2023)
Article
Nanoscience & Nanotechnology
Akira Satou, Takumi Negoro, Kenichi Narita, Tomotaka Hosotani, Koichi Tamura, Chao Tang, Tsung-Tse Lin, Paul-Etienne Retaux, Yuma Takida, Hiroaki Minamide, Tetsuya Suemitsu, Taiichi Otsuji
Summary: In this study, an asymmetric dual-grating-gate plasmonic terahertz (THz) detector based on an InGaAs-channel high-electron-mobility transistor (HEMT) in the gate-readout configuration was experimentally investigated. A new detection mechanism called the 3D rectification effect was discovered, which resulted in a giant enhancement of the detector responsivity by the cooperative effect of plasmonic nonlinearities and diode nonlinearity. The undesired long-tail waveform observed on the temporal pulse photoresponse of the device was found to be eliminated by introducing the inverted-HEMT structure. The internal current responsivity and noise-equivalent power of the device were estimated to be 0.49 A/W and 196 pW/root Hz at 0.8 THz. These results pave the way for the application of plasmonic THz detectors in beyond-5G THz wireless communication systems.
Article
Engineering, Electrical & Electronic
Xuecheng Jiang, Feng Xie, Yan Gu, Xiaohu Dong, Xiumei Zhang, Chun Zhu, Weiying Qian, Naiyan Lu, Guoqing Chen, Guofeng Yang
Summary: This study demonstrates a copper ion sensor based on Al0.18Ga0.82N/GaN high electron mobility transistor (HEMT) with L-cysteine functionalization. The sensor shows a high sensitivity of 82.22 mu A/(mg/L) and a detection limit of 0.01 mg/L, making it a promising approach for efficient and fast detection of Cu2+.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2022)
Article
Engineering, Electrical & Electronic
Yuji Ando, Ryutaro Makisako, Hidemasa Takahashi, Akio Wakejima, Jun Suda
Summary: The study revealed that the epitaxial layer structure affects the electrical characteristics of AlGaN/GaN HEMTs. GaN-on-GaN HEMTs showed an improved tradeoff between maximum drain current and breakdown characteristics compared to GaN-on-SiC HEMTs. Moreover, the impact of Fe diffusion on frequency dispersion was relatively limited in GaN-on-GaN devices.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2022)
Article
Engineering, Electrical & Electronic
C. Liu, Y. Q. Chen, Y. Liu, P. Lai, Z. Y. He, Y. F. En, T. Y. Wang, Y. Huang
Summary: This work investigates the degradation behavior and physical mechanism of AIGaN/GaN HEMTs under hot-electron stress in hydrogen and nitrogen atmosphere, showing that degradation in hydrogen atmosphere is more severe. Experimental results and COMSOL finite-element simulations support this conclusion.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2021)
Article
Materials Science, Multidisciplinary
Yijun Dai, Zihui Zhao, Tian Luo, Zhehan Yu, Li Chen, Wei Guo, Jichun Ye
Summary: This article demonstrates the polarization-induced self-isolation in AlGaN/GaN high-electron-mobility transistors (HEMTs) through the incorporation of lateral-polarity structures (LPS). The incorporation of LPS leads to the formation of a 2D electron gas (2DEG) in the III-polar heterojunction and depletion in the N-polar counterpart. The introduction of LPS provides a novel planar isolation technique with improved device performance by eliminating the isolation leakage path.
PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS
(2023)
Article
Optics
Siliang Liu, Xiaoxue Hu, Wenqing Lin, Zehui Lu, Sixing Xi, Liping Gong, Xiaolei Wang
Summary: This paper proposes a terahertz compressed sensing imaging technique based on line array detection. The feasibility of this technique is verified through theoretical derivation, MATLAB and ZEMAX simulation, and practical experiments. The results show that the proposed technique achieves high-quality image reconstruction and can be generalized to different objects. The technique significantly reduces the sampling rate compared to traditional methods and provides a new idea for terahertz high-resolution rapid imaging.
OPTICS AND LASERS IN ENGINEERING
(2023)
Article
Engineering, Electrical & Electronic
Yao Chen, Lin-An Yang, Zhi Jin, Yong-Bo Su, Yue Hao
Summary: DC performances of depletion-mode 100 nm In0.53Ga0.47As/InP HEMT integrated on a silicon substrate through SiO2-SiO2 bonding were studied via numerical simulation. The fixed charges at the InP/SiO2 interface have the most significant impact on the HEMT characteristics. Increasing the density of negative fixed charges at this interface leads to a shift in threshold voltage, a decrease in output current, and an increase in breakdown voltage. Adjusting the thickness of the InP layer may help mitigate the effects of fixed charges on the HEMT performance.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2021)
Review
Nanoscience & Nanotechnology
Taiichi Otsuji, Stephane Albon Boubanga-Tombet, Akira Satou, Deepika Yadav, Hirokazu Fukidome, Takayuki Watanabe, Tetsuya Suemitsu, Alexander A. Dubinov, Vyacheslav V. Popov, Wojciech Knap, Valentin Kachorovskii, Koichi Narahara, Maxim Ryzhii, Vladimir Mitin, Michael S. Shur, Victor Ryzhii
Summary: This paper reviews recent advancements in graphene-based plasmonic metamaterials for terahertz (THz) laser transistors. The researchers investigate various approaches using graphene plasmonic metamaterials to achieve room-temperature, dry-cell-battery operated intense THz lasing with fast direct modulation. The paper discusses device structures and design constraints for coherent light sources applicable to future THz wireless communication systems.
Article
Physics, Applied
M. Ryzhii, V Ryzhii, T. Otsuji, V Mitin, M. S. Shur
Summary: The response of lateral n(+)-i-n-n(+) graphene field-effect transistors (GFETs) to terahertz (THz) radiation is analyzed in this study. The nonlinearity caused by Coulomb drag and plasmonic oscillations in the GFET channel enables a resonantly strong response, which can be used for effective resonant detection of THz radiation.
APPLIED PHYSICS LETTERS
(2022)
Article
Optics
Yuma Takida, Kouji Nawata, Takashi Notake, Taiichi Otsuji, Hiroaki Minamide
Summary: A nonlinear optical mixing technique is used to detect and characterize sub-nanosecond terahertz (THz)-wave pulses. The frequency up-conversion and parametric amplification methods are employed for sensitive detection and intensity cross-correlation characterization. The experimental results reveal the temporal profile of THz-wave pulses generated by the injection-seeded THz-wave parametric generator (is-TPG) in the tunable range of 0.95-2.00 THz to have a pulse width of 150-190 ps at full width at half-maximum.
Article
Optics
D. S. Ponomarev, D. Lavrukhin, N. Zenchenko, T. Frolov, I. A. Glinskiy, R. A. Khabibullin, G. M. Katyba, V. N. Kurlov, T. Otsuji, K. Zaytsev
Summary: We present a sapphire-fiber-based lens that enhances the emitted THz power of a large-area photo-conductive antenna (PCA). Numerical simulations demonstrate the effectiveness of the lens in redistributing the photocarriers density in the PCA's gap. We also propose a step-by-step process to precisely and controllably place the sapphire-fiber on the surface of a single PCA.
Article
Physics, Applied
V. Ryzhii, T. Otsuji, M. Ryzhii, V. Mitin, M. S. Shur
Summary: This study demonstrates that resonant plasmonic detection significantly enhances the sensitivity of terahertz detectors based on a gated graphene field-effect transistor structure. By utilizing gated p and n regions as hole and electron reservoirs and terahertz resonant plasma cavities, the proposed device achieves terahertz signal rectification and excitation of plasmonic oscillations, leading to a substantial increase in detector responsivity.
PHYSICAL REVIEW APPLIED
(2022)
Article
Physics, Applied
V. Ryzhii, M. Ryzhii, V. Mitin, M. S. Shur, T. Otsuji
Summary: The Zener-Klein interband tunneling in graphene layers can be utilized for processing and generation of terahertz signals, with negative dynamic conductance and transit-time instability. By using periodic cascade structures, THz amplification and radiation can be achieved.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Optics
Dmitry S. Ponomarev, Denis Lavrukhin, Igor A. Glinskiy, Alexander E. Yachmenev, Nikolay Zenchenko, Rustam A. Khabibullin, Yurii G. Goncharov, Taiichi Otsuji, Kirill I. Zaytsev
Summary: This study proposes the design of a photoconductive antenna (PCA) emitter with a plasmonic grating featuring a very high plasmonic Au electrode with a thickness of 170 nm. Numerical simulations show that increasing h leads to the excitation of higher-order plasmon guided modes in the Au slit waveguides, resulting in an additional increase in the emitted THz power. The fabricated PCA demonstrates efficient operation with low-power laser excitation, achieving an overall THz power of 5.3 mu W over a bandwidth of approximately 4.0 THz, corresponding to a conversion efficiency of 0.2%. This design holds promise for modern THz spectroscopic and high-speed imaging applications.
Article
Physics, Applied
V. Ryzhii, C. Tang, T. Otsuji, M. Ryzhii, V. Mitin, M. S. Shur
Summary: We evaluated THz detectors based on graphene channel (GC) and a floating metal gate (MG) separated from GC by a black-phosphorus (b-P) or black-arsenic (b-As) barrier layer (BL). The operation of these GC-FETs involves heating of the two-dimensional electron gas in GC by THz radiation, leading to thermionic emission of hot electrons from GC to MG. This results in variation of the floating gate potential, affecting the source-drain current. At THz radiation frequencies close to plasmonic resonance frequencies in the gated GC, the variation in source-drain current and detector responsivity can be resonantly large.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Physics, Condensed Matter
I. M. Moiseenko, V. V. Popov, D. Fateev
Summary: For the first time, we investigate the interaction between the waveguide modes of a graphene structure and freely propagating terahertz electromagnetic waves. We discover a new physical phenomenon where incident THz waves can resonate with the surface TE modes of the graphene waveguide due to their dispersions near the light cone. We study the dispersion, amplification, and lasing of the surface TE modes in a dielectric waveguide covered with biased graphene layers, as well as the amplification and lasing of THz waves through TE mode resonances.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2023)
Article
Chemistry, Multidisciplinary
Omnia Samy, Mohamed Belmoubarik, Taiichi Otsuji, Amine El Moutaouakil
Summary: This study presents a thin THz absorber that can be easily tuned through the whole THz range (0.1-10 THz) by applying a low gate voltage (<1 V). The structure is based on cheap and abundant materials (MoS2/graphene). The absorptance frequency and width can be controlled by varying the structure and substrate dimensions, making it a promising alternative to expensive THz metamaterial-based absorbers.
Article
Nanoscience & Nanotechnology
V. Ryzhii, C. Tang, T. Otsuji, M. Ryzhii, S. G. Kalenkov, V. Mitin, M. S. Shur
Summary: In this study, we investigate the response of the micromechanical field-effect transistors (MMFETs) to terahertz (THz) signals. The MMFET utilizes microcantilevers (MC) as a floating gate and the movable mirror of Michelson optical interferometer. The mechanical vibrations of MC are converted into optical signals, allowing MMFET to operate as a THz radiation detector. The combination of mechanical and plasmonic resonances in MMFET, along with optical amplification, enables effective THz detection.
Article
Materials Science, Multidisciplinary
C. Bray, K. Maussang, C. Consejo, J. A. Delgado-Notario, S. Krishtopenko, S. Gebert, I. Yahniuk, S. Ruffenach, K. Dinar, J. Eroms, K. Indykiewicz, B. Jouault, J. Torres, Y. M. Meziani, W. Knap, A. Yurgens, S. D. Ganichev, F. Teppe
Summary: This article presents extensive experimental studies on the zero-field splittings in monolayer and bilayer graphene. Surprisingly, a decrease of the spin splittings with increasing temperature was observed. The origin of this phenomenon is discussed by considering possible physical mechanisms likely to induce a temperature dependence of the spin-orbit coupling.
Article
Chemistry, Multidisciplinary
Adil Rehman, Juan Antonio Delgado Notario, Juan Salvador Sanchez, Yahya Moubarak Meziani, Grzegorz Cywinski, Wojciech Knap, Alexander A. Balandin, Michael Levinshtein, Sergey Rumyantsev
Summary: This study demonstrates that mobility fluctuations are the dominant mechanism of low-frequency electronic noise in high-quality graphene, providing important insights for its applications in electronics and understanding the origin of 1/f noise in any electronic device.
Article
Nanoscience & Nanotechnology
Juan A. Delgado-Notario, Wojciech Knap, Vito Clerico, Juan Salvador-Sanchez, Jaime Calvo-Gallego, Takashi Taniguchi, Kenji Watanabe, Taiichi Otsuji, Vyacheslav V. Popov, Denis V. Fateev, Enrique Diez, Jesus E. Velazquez-Perez, Yahya M. Meziani
Summary: This study fabricated a graphene terahertz field-effect transistor with an asymmetric-dual-grating-gate and a continuous graphite back-gate, which enhanced the THz rectified signal by forming abrupt junctions with different potential barriers. This paves the way for new record performances of graphene THz nano-photodetectors.
