Article
Chemistry, Multidisciplinary
Elena Titova, Dmitry Mylnikov, Mikhail Kashchenko, Ilya Safonov, Sergey Zhukov, Kirill Dzhikirba, Kostya S. Novoselov, Denis A. Bandurin, Georgy Alymov, Dmitry Svintsov
Summary: Graphene's high carrier mobility, compatibility with on-chip waveguides and transistors, and small heat capacitance make it a promising material for the detection of terahertz (THz) radiation. However, the weak reaction of graphene's physical properties to the detected radiation is due to the absence of a band gap. This study investigates the effect of electrically induced band gap on THz detection in graphene bilayer with split-gate p-n junction, and demonstrates that the induction of a band gap leads to increased current and voltage responsivities.
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
Chemistry, Multidisciplinary
Jesse Balgley, Jackson Butler, Sananda Biswas, Zhehao Ge, Samuel Lagasse, Takashi Taniguchi, Kenji Watanabe, Matthew Cothrine, David G. Mandrus, Jairo Velasco, Roser Valenti, Erik A. Henriksen
Summary: In this study, we demonstrate ultrasharp lateral p-n junctions in graphene using electronic transport, scanning tunneling microscopy, and first-principles calculations. These junctions are formed at the boundary between differently doped regions of a graphene sheet, with one side being intrinsic and the other side being charge-doped by proximity to an alpha-RuCl3 flake. Our results show potential variations on a sub 10 nm length scale in heterostructures of graphene, hexagonal boron nitride, and alpha-RuCl3. First-principles calculations reveal a sharp decay of charge-doping from the edge of the alpha-RuCl3 flake within just a few nanometers.
Article
Chemistry, Multidisciplinary
Dmitry A. Mylnikov, Elena I. Titova, Mikhail A. Kashchenko, Ilya V. Safonov, Sergey S. Zhukov, Valentin A. Semkin, Kostya S. Novoselov, Denis A. Bandurin, Dmitry A. Svintsov
Summary: This study investigates the sub-terahertz photoconductivity of gapped bilayer graphene with electrically induced p-n junctions. The results show that these junctions have a strong positive contribution to resistance, temperature resistance coefficient, and photoresistivity at cryogenic temperatures.
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
Chemistry, Multidisciplinary
Daniel J. Rizzo, Sara Shabani, Bjarke S. Jessen, Jin Zhang, Alexander S. McLeod, Carmen Rubio-Verdu, Francesco L. Ruta, Matthew Cothrine, Jiaqiang Yan, David G. Mandrus, Stephen E. Nagler, Angel Rubio, James C. Hone, Cory R. Dean, Abhay N. Pasupathy, D. N. Basov
Summary: The researchers successfully created nanometer-scale lateral p-n junctions using graphene/alpha-RuCl3 heterostructure near graphene nanobubbles. Through STM/STS and s-SNOM techniques, they investigated the electronic and optical responses of nanobubble p-n junctions, achieving p-n junctions with a width of around 3 nm and an electric field of approximately 10(8) V/m. The study also utilized ab initio density functional theory calculations to corroborate experimental data and provide insights into charge transfer mechanisms in 2D materials.
Article
Biochemistry & Molecular Biology
Yan Fan, Tao Wang, Yinwei Qiu, Yinli Yang, Qiubo Pan, Jun Zheng, Songwei Zeng, Wei Liu, Gang Lou, Liang Chen
Summary: Graphene p-n junctions have important applications in optical interconnection and low-power integrated circuits. Our study introduces a new type of pure graphene oxide (pGO) vertical p-n junction, demonstrating significant rectification effects and photoelectric responses. Additionally, our work offers a simple and convenient method for preparing undoped GO vertical p-n junctions, showing great potential for applications in electronics and sensors.
Article
Physics, Applied
V Ryzhii, M. Ryzhii, A. Satou, T. Otsuji, V Mitin, M. S. Shur
Summary: This study reveals that drag caused by interband tunneling has a significant influence on the current-voltage characteristics and impedance of graphene tunneling transistor structures, potentially leading to plasma instability and self-excitation of plasma oscillations in the terahertz frequency range.
PHYSICAL REVIEW APPLIED
(2021)
Article
Chemistry, Multidisciplinary
Pin-Chiao Huang, Hongye Sun, Mamun Sarker, Christopher M. Caroff, Gregory S. Girolami, Alexander Sinitskii, Joseph W. Lyding
Summary: This paper demonstrates the fabrication of nanometer-scale metal contacts on individual graphene nanoribbons (GNRs) and the use of these contacts to control the electronic character of the GNRs. Using a low-voltage direct-write STM-based process, sub-5 nm metallic hafnium diboride (HfB2) contacts are patterned directly on top of single GNRs in an ultrahigh-vacuum scanning tunneling microscope (UHV-STM), with all the fabrication performed on a technologically relevant semiconductor silicon substrate. Scanning tunneling spectroscopy (STS) data verify the expected metallic and semiconducting character of the contacts and GNR, and also show induced band bending and p-n junction formation in the GNR due to the metal-GNR work function difference. Contact engineering with different work function metals eliminates the need for complex chemical doping to create GNRs with different characteristics. This paper demonstrates the successful fabrication of precise metal contacts and local p-n junction formation on single GNRs.
Article
Engineering, Electrical & Electronic
Chia-Feng Lin, Yu-Ting Zhang, Cheng-Jie Wang, Yi-Yun Chen, Guo-Yi Shiu, Ying-Ke, Jung Han
Summary: In this study, InGaN-based resonant cavity light-emitting diode structures with top and bottom porous-GaN distributed Bragg reflectors were demonstrated. The electroluminescence spectra line-widths were significantly reduced due to the resonant microcavity effect, improving the performance of the devices.
IEEE ELECTRON DEVICE LETTERS
(2021)
Article
Optics
Pei-Jung Wu, Wei-Cheng Tsai, Chan-Shan Yang
Summary: In this study, an electrically tunable multi-band terahertz (THz) metamaterial filter based on graphene and multiple-square-loop structures was designed. The structure consists of multiple metal square loops of different sizes, which correspond to different THz frequencies, achieving the expected efficacy of a multi-band wave filter. By sweeping external voltages, the capability of the high-sensitivity THz filter can be modulated from single-band to multi-band filtering by changing graphene's Fermi levels. This hybrid THz wave filter study shows promise for the development of selecting channels in THz and 6G communications.
Article
Physics, Multidisciplinary
Peipei Zhang, Chao Wang, Yu-Xian Li, Lixue Zhai, Juntao Song
Summary: The transport properties of electrons in graphene p-n junction with uniform Kekule lattice distortion were studied using the tight-binding model and the Landauer-Buttiker formalism combined with the nonequilibrium Green's function method. Different shapes of Kekule graphene p-n junctions result in different electron transport behaviors, with Klein tunneling and resonance tunneling playing important roles. Moreover, under strong magnetic fields, resonance tunneling was observed, and disorder can enhance conductance.
NEW JOURNAL OF PHYSICS
(2023)
Article
Nanoscience & Nanotechnology
Kang Wang, Takashi Taniguchi, Kenji Watanabe, Jiamin Xue
Summary: Two-dimensional semiconductors show great potential as channel materials for field-effect transistors. Unlike traditional three-dimensional semiconductors, their surface with saturated chemical bonds maintains excellent properties even at monolayer thickness. However, the edges of these materials, which often go unnoticed, have important effects on devices. This study demonstrates that the edges of exfoliated and etched MoS2 are naturally p-type doped and can form p-n junctions with the bulk of the flake, which can be utilized to create rectifying or optoelectronic devices without the need for external doping.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Chemistry, Physical
Fahrettin Sarcan, Umit Dogan, Ahmad Althumali, Hari B. Vasili, Leonardo Lari, Adam Kerrigan, Furkan Kuruoglu, Vlado K. Lazarov, Ayse Erol
Summary: This study reports the electrical and optical properties of a novel NiO-based homojunction p-i-n photodiode. The photodiode exhibits diode characteristics and a constant photoresponse under reverse bias. The responsivity of the photodiode is determined to be 295 mA/W at 3.9 eV.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Computer Science, Information Systems
Junru An, Tian Sun, Bin Wang, Jianlong Xu, Shaojuan Li
Summary: Graphene-based infrared photodetectors with in-plane p-n-p junction exhibit excellent photoresponse and significantly reduced dark current, showing promising potential for high-performance IR photodetection applications.
SCIENCE CHINA-INFORMATION SCIENCES
(2021)
Article
Materials Science, Multidisciplinary
Victor Ryzhii, Maxim Ryzhii, Akira Satou, Vladimir Mitin, Michael S. Shur, Taiichi Otsuji
Summary: The injection of ballistic electrons can lead to terahertz radiation and be utilized for optimizing devices through effective Coulomb drag and plasma instability.
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
(2022)
Article
Engineering, Biomedical
Michael Shur, Outman Akouissi, Olivier Rizzo, Didier J. Colin, John M. Kolinski, Stephanie P. Lacour
Summary: The study proposes a simple fabrication and processing sequence to deliver brain-like hydrogel implants into the nervous tissue. Real-time monitoring of hydrogel re-swelling kinetics in vivo is achieved using microcomputed tomography, and the study reveals how implant geometry and mechanical interplay govern in vivo buckling. These findings provide important guidance for the engineering of biomimetic brain implants.
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
Materials Science, Multidisciplinary
M. S. Shur, X. Liu, T. Ytterdal
Summary: Novel metal oxide materials and improved fabrication processes have significantly enhanced the performance of thin film transistor (TFT), with approaches of 150 cm²/Vs in the effective field-effect mobility. An improved compact TFT model based on three models has been reported in this study, which considers the non-exponential slope in the subthreshold regime and the non-trivial capacitance dependence on gate bias. The TFTs have shown a substantial response to impinging THz and sub-THz radiation, and the detection sensitivity can be improved by using a complementary inverter and phase-matched THz signal feeding.
ECS JOURNAL OF SOLID STATE SCIENCE AND TECHNOLOGY
(2023)
Article
Physiology
Maxim Ryzhii, Elena Ryzhii
Summary: This paper presents a compact and computationally lightweight rabbit AVN model based on the Aliev-Panfilov two-variable cardiac cell model. The model demonstrates broad functionality, including normal sinus rhythm, AVN automaticity, filtering of high-rate atrial rhythms during atrial fibrillation and atrial flutter, and realistic conduction curves in the control case and the cases of FP and SP ablation. The model can be used as a stand-alone module or as a part of complex atrial or whole heart simulation systems, and helps to understand some puzzling functions of AVN.
FRONTIERS IN PHYSIOLOGY
(2023)
Review
Physics, Applied
V. Ryzhii, C. Tang, T. Otsuji, M. Ryzhii, V. Mitin, M. S. Shur
Summary: This article analyzes the operation of terahertz (THz) bolometric detectors based on field-effect transistor (FET) structures with graphene channels (GCs) and black-phosphorus and black-arsenic gate barrier layers (BLs). The detectors utilize the heating of a two-dimensional electron gas (2DEG) by THz radiation, leading to the emission of hot electrons into the gate via the BL. The excitation of plasmonic oscillations in the GC by THz signals results in a resonant detector response and increased responsivity.
PHYSICAL REVIEW APPLIED
(2023)
Article
Physics, Applied
Babak Nikoobakht, Yuqin Zong, Okan Koksal, Amit Agrawal, Christopher Montgomery, Jaime Rumsey, Jacob Leach, Michael Shur
Summary: In this study, we investigate the impact of the fin aspect ratio on the external quantum efficiency (EQE) and UV emission of AlGaN fin/p-GaN heterojunctions. With decreasing aspect ratio, the UV emission of the fins increases and EQE is enhanced by 7 times. This can be attributed to the conservation of the volume of the carrier depletion region within a fin.
APPLIED PHYSICS LETTERS
(2023)
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
Physics, Multidisciplinary
Yuhui Zhang, Michael Shur
Summary: We demonstrate that a periodic multi-grated-gate structure can be used in THz plasmonic FETs (TeraFETs) to enhance THz detection sensitivity. By introducing spatial non-uniformity through separated gate sections, regions with different carrier concentrations and velocities are created, resulting in harmonic behaviors. The frequency spectrum of the DC voltage response consists of enhanced and suppressed regions. In the enhanced region, the response voltage amplitude can be increased up to approximately 100% compared to a uniform channel device. The distribution pattern of these regions is directly related to the number of gate sections (N (s)). A mapping of response amplitude in an N (s)-frequency scale is created, which aids in distinguishing enhanced/suppressed regions and locating optimal operating parameters.
FRONTIERS IN PHYSICS
(2023)
Proceedings Paper
Engineering, Electrical & Electronic
Muhammad Mahmudul Hasan, Yuhiu Zhang, Nezih Pala, Michael Shur
Summary: p-diamond is a strong candidate for sub-THz and THz applications due to its favorable properties, such as large hole effective mass, high optical phonon energy, high momentum relaxation time, and high mobility. Recent research on p-diamond TeraFETs has shown their potential for sub-THz and THz radiation detection and transmission. N-diamond TeraFETs also hold promise for emerging terahertz applications. One of the main factors affecting plasma wave dampening in our study is the viscosity of the charge carrier medium in the channel.
2023 IEEE 16TH DALLAS CIRCUITS AND SYSTEMS CONFERENCE, DCAS
(2023)
Proceedings Paper
Engineering, Electrical & Electronic
Naznin Akter, Masudur R. Siddiquee, John Suarez, Michael Shur, Nezih Pala
Summary: THz testing using deep learning models achieves high classification accuracy of 98% for distinguishing between original and damaged ICs based on the response of a modern FET acting as a terahertz detector.
IMAGE SENSING TECHNOLOGIES: MATERIALS, DEVICES, SYSTEMS, AND APPLICATIONS IX
(2022)
Proceedings Paper
Engineering, Biomedical
Michael Shur
Summary: Terahertz radiation is used for detection, sensing, and imaging of biological objects, especially in cancer diagnostics. This technology allows for more accurate cancer detection based on the magnitude and phase information of the THz signal.
ADVANCES IN TERAHERTZ BIOMEDICAL IMAGING AND SPECTROSCOPY
(2022)
Proceedings Paper
Engineering, Biomedical
Taiichi Otsuji, Victor Ryzhii, Michael Shur
Summary: This paper reviews the development of graphene plasmonic THz technology and suggests the potential for commercial applications. The unique properties of graphene and its ability to form heterostructures with other materials make it a promising candidate for revolutionizing THz technology.
ADVANCES IN TERAHERTZ BIOMEDICAL IMAGING AND SPECTROSCOPY
(2022)
Proceedings Paper
Engineering, Electrical & Electronic
Michael Shur, Xueqing Liu, Trond Ytterdal
Summary: Short channel Si CMOS is used in THz detectors and THz imaging arrays. The excitation of phase-shifted resonant or overdamped plasma waves enables the operation of TeraFETs as THz spectrometers. Future developments in Si CMOS sub-THz and THz applications will involve Si CMOS integrated circuits such as line-of-sight detectors, traveling wave sub-THz amplifiers, and frequency-to-digital converters.
TERAHERTZ, RF, MILLIMETER, AND SUBMILLIMETER-WAVE TECHNOLOGY AND APPLICATIONS XV
(2022)
