Yukio Kawano

We report a graphene-based frequency-selective terahertz (THz) and infrared (IR) detector. The experimental results have demonstrated that the graphene transistor under a magnetic field is capable of detecting THz and IR waves in a very wide band of frequencies (0.76-33 THz) and that the detection frequency is tuned by changing the magnetic field. We have further imaged electric potential distribution in the graphene detector and have observed local step structure associated with impurities. The

The authors have studied the transport properties of carbon nanotube quantum dots under terahertz (THz) wave irradiation. The experimental data have shown that the satellite currents are generated with the THz irradiation, and that the peak position of the satellite currents varies linearly with the THz photon energy. These results provide experimental evidence for photon-assisted tunneling in the THz region. The present observation provides the interesting possibility of developing a highly sen

CMOS technology is being advanced rapidly and applications are now expanding into the millimeter-wave regime on a global basis. 60 GHz wireless systems in CMOS have already been reported. In addition, 77 GHz automotive radar is becoming the target for CMOS technology. This paper describes what is believed to be the first transceiver chip for 77 GHz radar in standard 90 nm CMOS.

Carbon-nanotube-related (CNT-related) materials and structures are highly anticipated as potential building blocks for future flexible electronics and photonics. Despite the various promising applications of CNT-related materials, one obstacle is the lack of ability to globally control and tune the Fermi level of microscale-thick CNT films because these films require a certain thickness to maintain their free-standing shape and freely bendable flexibility. In this work, we report on Fermi-level-

Abstract In the wide range of the electromagnetic wave spectrum, the terahertz (THz) frequency region has for a long time been an unexplored region and its technological development has been left behind. Nowadays, however, science and technology based on THz electromagnetic waves have been increasingly progressing and are still growing. In the THz region, both features of ‘wave’ and ‘light’ appear, enabling the manipulation of the THz wave from both approaches of electronics and optics/photonics

We report on a highly sensitive terahertz (THz) detector based on a carbon nanotube (CNT) transistor, which is integrated with a two-dimensional electron gas (2DEG) in a GaAs/AlGaAs heterostructure. The operation principle of this device is that the CNT transistor senses electrical polarization induced by terahertz-excited electron-hole pairs in the 2DEG. The magnetic field dependence of the terahertz response signal (CNT current) is shown to follow features of cyclotron resonance of the 2DEG, i

Abstract The integration of flexible electronics with optics can help realize a powerful tool that facilitates the creation of a smart society wherein internal evaluations can be easily performed nondestructively from the surface of various objects that is used or encountered in daily lives. Here, organic‐material‐based stretchable optical sensors and imagers that possess both bending capability and rubber‐like elasticity are reviewed. The latest trends in nondestructive evaluation equipment tha

Abstract Terahertz (THz) imaging is expected to become powerful tools for non‐destructive inspections. To ensure the practical use of THz non‐destructive monitoring, versatile THz imagers with adjustable designs that can eliminate the complexities and the bulkiness of the device are urgently required. Herein, a self‐aligned filtration process for a 2D, free‐standing carbon nanotube film array and its application to a THz video camera patch are reported. The presented techniques enable a) to free

Chemical monitoring communicates diverse environmental information from industrial and biological processes. However, promising and sustainable systems and associated inspection devices that dynamically enable on-site quality monitoring of target chemicals confined inside transformable and opaque channels are yet to be investigated. This paper designs stretchable photo-sensor patch sheets for nonsampling, source-free, and label-free on-site dynamic chemical monitoring of liquids flowing inside s

As flexible wearable sensors and imagers are receiving attention from diverse social sectors, the freely attachable photothermoelectric (PTE) conversion technique should be evaluated to develop a highly usable safety sensor network. Although carbon nanotube (CNT)‐related materials should be effective, the key parameters/structures that maximize PTE conversion have not been clarified, thus hindering optimum device design and practical use. Herein, the flexible, sensitive broadband photodetection

We present novel terahertz (THz) detectors, using nanoelectronic devices, such as 2-D semiconductor and carbon nanotube (CNT). Our detector is useful for high-resolution THz imaging, which requires highly sensitive detection. We have developed a frequency-tunable THz-photon detector and an on-chip near-field imaging detector. The detection mechanism of the former is that the CNT transistor detects electrical polarization generated by THz-excited electron-hole pairs in the 2-D semiconductor. In t

The photo-thermoelectric (PTE) effect in electronic materials effectively combines photo-absorption-induced local heating and associated thermoelectric conversion for uncooled and broadband photo-detection. In particular, this work comprehensively summarizes the operating mechanism of carbon nanotube (CNT)-film-based PTE sensors and ubiquitous non-destructive inspections realized by exploiting the material properties of CNT films. Formation of heterogeneous material junctions across the CNT-film

Flexible imagers are currently under intensive development as versatile optical sensor arrays, designed to capture images of surfaces and internals, irrespective of their shape. A significant challenge in developing flexible imagers is extending their detection capabilities to encompass a broad spectrum of infrared light, particularly terahertz (THz) light at room temperature. This advancement is crucial for thermal and biochemical applications. In this study, a flexible infrared imager is desig