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In our pursuit of high-power terahertz (THz) wave generation, we propose innovative edge-terminated single-drift region (SDR) multi-quantum well (MQW) impact avalanche transit time (IMPATT) structures based on the AlxGa1−xN/GaN/AlxGa1−xN material system, with a fixed aluminum mole fraction of x = 0.3. Two distinct MQW diode configurations, namely p+-n junction-based and Schottky barrier diode structures, were investigated for their THz potential. To enhance reverse breakdown characteristics, we propose employing mesa etching and nitrogen ion implantation for edge termination, mitigating issues related to premature and soft breakdown. The THz performance is comprehensively evaluated through steady-state and high-frequency characterizations using a self-consistent quantum drift-diffusion (SCQDD) model. Our proposed Al0.3Ga0.7N/GaN/Al0.3Ga0.7N MQW diodes, as well as GaN-based single-drift region (SDR) and 3C-SiC/Si/3C-SiC MQW-based double-drift region (DDR) IMPATT diodes, are simulated. The Schottky barrier in the proposed diodes significantly reduces device series resistance, enhancing peak continuous wave power output to approximately 300 mW and DC to THz conversion efficiency to nearly 13% at 1.0 THz. Noise performance analysis reveals that MQW structures within the avalanche zone mitigate noise and improve overall performance. Benchmarking against state-of-the-art THz sources establishes the superiority of our proposed THz sources, highlighting their potential for advancing THz technology and its applications. [ABSTRACT FROM AUTHOR]

This study demonstrates the conversion of metallic titanium (Ti) to titanium oxide just by conducting electrical current through Ti thin film in vacuum and increasing the temperature by Joule heating. This led to the improvement of electrical and thermal properties of a microbolometer. A microbolometer with an integrated Ti thermistor and heater width of 2.7 µm and a length of 50 µm was fabricated for the current study. Constant-voltage stresses were applied to the thermistor wire to observe the effect of the Joule heating on its properties. Thermistor resistance ~14 times the initial resistance was observed owing to the heating. A negative large temperature coefficient of resistance (TCR) of −0.32%/K was also observed owing to the treatment, leading to an improved responsivity of ~4.5 times from devices with untreated Ti thermistors. However, this does not improve the noise equivalent power (NEP), due to the increased flicker noise. Microstructural analyses with transmission electron microscopy (TEM), transmission electron diffraction (TED) and energy dispersive X-ray (EDX) confirm the formation of a titanium oxide (TiOx) semiconducting phase on the Ti phase (~85% purity) deposited initially, further to the heating. Formation of TiOx during annealing could minimize the narrow width effect, which we reported previously in thin metal wires, leading to enhancement of responsivity. [ABSTRACT FROM AUTHOR]

A Schottky barrier high-electron-mobility avalanche transit time (HEM-ATT) structure is proposed for terahertz (THz) wave generation. The structure is laterally oriented and based on AlGaN/GaN two-dimensional electron gas (2-DEG). Trenches are introduced at different positions of the top AlGaN barrier layer for realizing different sheet carrier density profiles at the 2-DEG channel; the resulting devices are equivalent to high–low, low–high and low-high–low quasi-Read structures. The DC, large-signal and noise simulations of the HEM-ATTs were carried out using the Silvaco ATLAS platform, non-sinusoidal-voltage-excited large-signal and double-iterative field-maximum small-signal simulation models, respectively. The breakdown voltages of the devices estimated via simulation were validated by using experimental measurements; they were found to be around 17–18 V. Under large-signal conditions, the series resistance of the device is estimated to be around 20 Ω. The large-signal simulation shows that the HEM-ATT source is capable of delivering nearly 300 mW of continuous-wave peak power with 11% conversion efficiency at 1.0 THz, which is a significant improvement over the achievable THz power output and efficiency from the conventional vertical GaN double-drift region (DDR) IMPATT THz source. The noise performance of the THz source was found to be significantly improved by using the quasi-Read HEM-ATT structures compared to the conventional vertical Schottky barrier IMPATT structure. These devices are compatible with the state-of-the-art medium-scale semiconductor device fabrication processes, with scope for further miniaturization, and may have significant potential for application in compact biomedical spectroscopy systems as THz solid-state sources. [ABSTRACT FROM AUTHOR]

In this study, uncooled antenna-coupled microbolometer arrays were fabricated to detect terahertz waves by using nanoscale meander-shaped Ti thermistors with design widths of DW = 0.1 and 0.2 μm, respectively, on SiO2 and SiNx substrates. Each unit device with a thermistor with DW = 0.1 μm yielded double the electrical responsivity (787 V/W) of unit devices with thermistors with DW = 0.2 μm (386 V/W) at the maximum allowable bias current (Ib = 50 for DW = 0.1 μm and 100 μA for DW = 0.2 μm, respectively). However, the calculated noise-equivalent power (NEP) of unit devices with thermistors with DW = 0.1 μm was 1.85 × 10 − 10 W / Hz at Ib = 50 μA and 1.58 × 10 − 10 W / Hz at Ib = 100 μA for unit devices with thermistors with DW = 0.2 μm. Hence, the reduction in DW did not lead to an improvement in NEP. This study validates our previous investigation into the effect of width on such device parameters such as the temperature coefficient of resistance (TCR) and resistivity in the context of device miniaturization. The smaller grain size in thinner metal interconnects (thermistors) can be linked to the lower TCR and increased resistivity of the devices. Thus, the enhancement in responsivity in the design was largely due to the nanoscale meander design that, however, was detrimental to the noise response of the devices. These devices with nanoscale Ti meander thermistors deliver high responsivity in unit devices with scope for further miniaturization and have significant potential for application as on-chip integrable detector arrays. [ABSTRACT FROM AUTHOR]

This paper proposes a new optical biosensor composed of a silicon-on-insulator (SOI) p–n junction photodiode (PD) with a surface plasmon (SP) antenna. When the phase-matching condition between two lateral wavelengths of the diffracted light from the SP antenna and the waveguiding mode in the SOI PD is satisfied, we observe sharp peaks in the spectroscopic light sensitivity. Since the peak wavelength depends on the RI change around the SP antenna corresponding to the phase-matching condition, the SOI PDs with an SP antenna can be applied to the optical biosensor. The RI detection limit is evaluated in the measurements with bulk solutions, and 1.11 × 10−5 RIU (refractive index unit) can be obtained, which is comparable to that of a surface plasmon resonance (SPR) sensor, which is well known as a representative optical biosensor. In addition, the response for intermolecular bonds is estimated by the electromagnetic simulations using the finite-difference time-domain (FDTD) method to clarify its ability to detect biomolecular interactions. The results of this paper will provide new ground for high-throughput label-free biosensing, since a large number of SOI PDs with an SP antenna can be easily integrated on a single chip via an SOI complementary metal-oxide-semiconductor (CMOS) fabrication process. [ABSTRACT FROM AUTHOR]

Featured Application: High-frequency amplification, oscillation, detection, qubits readout by gate-based sensing, etc., based on a single-electron transistor. Based on the time-dependent master equation and taking the dynamic gate current into account, a new single-electron transistor (SET) model is proposed, which can represent intrinsic terminal capacitances and transcapacitances. By using this model, bias, frequency and temperature dependences of these capacitances are evaluated. Since the model is implemented in the SPICE circuit simulator, it can be used to analyze the high-frequency behavior of circuits, including SETs and is applied to the characterization of a SET-based inverting amplifier this time. [ABSTRACT FROM AUTHOR]

The antenna-coupled microbolometer with suspended titanium heater and thermistor was attractive as a terahertz (THz) detector due to its structural simplicity and low noise levels. In this study, we attempted to improve the responsivity and noise-equivalent power (NEP) of the THz detector by using high-resistance heater stacked on the meander thermistor. A wide range of heater resistances were prepared by changing the heater width and thickness. It was revealed that the electrical responsivity and NEP could be improved by increasing the heater's resistance. To make the best use of this improvement, a high-impedance folded dipole antenna was introduced, and the optical performance at 1 THz was found to be better than that of the conventional halfwave dipole antenna combined with a low-resistance heater. Both the electrical and optical measurement results indicated that the increase in heater resistance could reduce the thermal conductance in the detector, thus improved the responsivity and NEP even if the thermistor resistance was kept the same. [ABSTRACT FROM AUTHOR]

Metallic single-electron transistors (SETs) with Nb nanodots were fabricated and their high-frequency rectifying characteristics were evaluated. By reducing the gap size of the electrodes and film deposition area to nanometer scale, improved SET characteristics with gate control and better frequency response of the rectifying current with gentler decrease than 1/ f at high frequency were achieved. A comparison between the characteristics of micrometer- and nanometer-size devices is made, and the reasons for their differences are discussed with the aid of simulations based on the experimentally extracted parameters. [ABSTRACT FROM AUTHOR]

Light enhancement occurs strongly within the plasmonic clusters by interaction with surface plasmons. Surface-enhanced Raman spectroscopic (SERS) characteristics of a series of silver@silica trimer core–shell (CS) nanosphere (NS) clusters are investigated in this paper. It is significant to understand the electric field (EF) enhancement mechanism behind the SERS technique. The effect of symmetry breaking is studied for the series starting from the highly symmetric trimer cluster and transformed to linear dimer geometry which progresses through the gradual reduction in the vertex NS. The optical activity such as the evolution of LSPR peak is discussed, the formation of hot spots is demonstrated and the strength of the local EF enhancement is calculated and correlated with the plasmon dipolar modes by using plasmon hybridization theory to understand the underlying physical concepts. [ABSTRACT FROM AUTHOR]

A novel measurement system consisting of scanning electron microscopy and infrared (IR) thermography has been constructed to measure the thermal conductivity and the thermal diffusivity on a micro-/nanometer scale. In this study, we measured them for a stainless-steel wire with a diameter of 50 μm to demonstrate the validity of our system. The time evolution of temperature distribution on the whole of the stainless-steel wire was recorded by the IR thermograph when the wire was irradiated by the electron beam (EB). A time response of the wire temperature corresponding to the on/off of the EB irradiation was clearly observed, indicating that local EB heating was realized. In addition, the experimental time evolution of temperature at its transient phenomena was in good agreement with the theoretical calculation based on a one-dimensional (1D) equivalent-circuit model of heat flow coupled with electric current, where the thermal parameters, such as thermal conductivity and heat capacitance, were set to bulk values. Therefore, it can be concluded that our system is valid to evaluate the thermal conductivity of the 1D wire sample. For evaluating the thermal diffusivity of the wire sample, we applied a periodic EB irradiation by a rectangular wave with a frequency of 0.25 Hz. The thermal diffusivity was evaluated to be (2.8 ± 0.6) × 10−5 m2 s−1, which was seven times as large as that of bulk stainless steel. Our system can be applied to an AC calorimetry method for a 1D system sample after the analysis procedure is further modified. [ABSTRACT FROM AUTHOR]

In this paper, the real-time signal processing for the silicon-on-insulator MOSFET single-photon detector is investigated. The output waveforms of the detector consist of rising and falling edges that correspond to hole generation by the photon incidence and spontaneous hole recombination, respectively, and current levels related to the number of stored holes. The signal processor has been developed to detect the rising edge and measure the step height that represents the number of photogenerated holes at the same time and implemented to a field programmable gate array for real-time processing. In order to verify its operation, waveforms at different light intensities are processed, and it is successfully demonstrated that the statistical distribution of generated holes in a unit observation time follows the Poisson distribution. [ABSTRACT FROM AUTHOR]

Aim: Further to our reports on chip-integrable uncooled terahertz microbolometer arrays, compatible with medium-scale semiconductor device fabrication processes, the possibility of the development of chip-integrable medical device is proposed here. Methods: The concept of graphene-based nanopatch antennas with design optimization by the finite element method (FEM) is explored. The high-frequency structure simulator (HFSS) utilized fine FEM solver for analyzing empirical mode decomposition preprocessing and for modeling and simulating graphene antennas. Results: Graphene nanopatch antennas exhibited tunable features with varying patch dimensions and dependence on substrate material permittivity. Conclusion: This work implements reconfigurable graphene nanopatch antenna compatible with terahertz microbolometer arrays. This design concept further develops on-chip medical devices for possible screening of cancer cell with terahertz image processing. [ABSTRACT FROM AUTHOR]

A core‐shell structure with CuO core and carbon quantum dots (CQDs) and carbon hollow nanospheres (CHNS) shell was prepared through facile in‐situ hydrothermal process. The composite was used for non‐enzymatic hydrogen peroxide sensing and electrochemical overall water splitting. The core‐shell structure was established from the transmission electron microscopy image analysis. Raman and UV‐Vis spectroscopy analysis confirmed the interaction between CuO and CQDs. The electrochemical studies showed the limit of detection and sensitivity of the prepared composite as 2.4 nM and 56.72 μA μM−1 cm−2, respectively. The core‐shell structure facilitated better charge transportation which in turn exhibited elevated electro‐catalysis towards hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and overall water splitting. The overpotential of 159 mV was required to achieve 10 mA cm−2 current density for HER and an overpotential of 322 mV was required to achieve 10 mA cm−2 current density for OER in 1.0 M KOH. A two‐electrode system was constructed for overall water splitting reaction, which showed 10 and 50 mA cm−2 current density at 1.83 and 1.96 V, respectively. The prepared CuO@CQDs@CHNS catalyst demonstrated excellent robustness in HER and OER catalyzing condition along with overall water splitting reaction. Therefore, the CuO@CQDs@CHNS could be considered as promising electro‐catalyst for H2O2 sensing, HER, OER and overall water splitting. [ABSTRACT FROM AUTHOR]

A common observation in metal-based (specifically, those with AlOx tunnel junctions) single-electron tunneling (SET) devices is a time-dependent instability known as the long-term charge offset drift. This drift is not seen in Si-based devices. Our aim is to understand the difference between these, and ultimately to overcome the drift in the metal-based devices. A comprehensive set of measurements shows that (1) brief measurements over short periods of time can mask the underlying drift, (2) we have not found any reproducible technique to eliminate the drift, and (3) two-level fluctuators (TLFs) in the metal-based devices are not stable. In contrast, in the Si-based devices the charge offset drifts by less than 0.01e over many days, and the TLFs are stable. We also show charge noise measurements in a SET device over four decades of temperature. We present a model for the charge offset drift based on the observation of nonequilibrium heat evolution in glassy materials, and obtain a numerical estimate in good agreement with our charge offset drift observations. We conclude that, while the Si devices are not perfect and defect-free, the defects are stable and noninteracting; in contrast, the interacting, unstable glasslike defects in the metal-based devices are what lead to the charge offset drift. We end by suggesting some particular directions for the improvement in fabrication, and in particular, fabrication with crystalline metal-oxide barriers, that may lead to charge offset drift-free behavior. [ABSTRACT FROM AUTHOR]

Low-energy electron irradiation causes damage in single-walled carbon nanotubes and changes the electric behavior of a nanotube field-effect transistor from metallic to semiconducting at low temperature. The irradiation damage was found to form an energy barrier of several 10 meV in the nanotube channel. We show that the transition behavior can be reasonably explained by the barrier formation and gate-induced band bending. [ABSTRACT FROM AUTHOR]

The ultimate goal of future information processing might be the realization of a circuit in which one bit is represented by a single electron. Such a challenging circuit would comprise elemental devices whose tasks are to drag, transfer, and detect single electrons. In achieving these tasks, the Coulomb blockade, which occurs in tiny conducting materials, plays an important role. This paper describes the current status of research on such single-charge-control devices from the viewpoints of circuit applications. [ABSTRACT FROM AUTHOR]

We propose a planar device architecture compatible with the CMOS process technology as the optimal current benchmark of a Si-nanowire (NW) thermoelectric (TE) power generator. The proposed device is driven by a temperature gradient that is formed in the proximity of a perpendicular heat flow to the substrate. Therefore, unlike the conventional TE generators, the planar short Si-NWs need not be suspended on a cavity structure. Under an externally applied temperature difference of 5 K, the recorded TE power density is observed to be $12~\mu \text{W}$ /cm2 by shortening the Si-NWs length and suppressing the parasitic thermal resistance of the Si substrate. The demonstration paves a pathway to develop cost-effective autonomous internet-of-things applications that utilize the environmental and body heats. [ABSTRACT FROM AUTHOR]

The degradation of high-frequency characteristics of a 1.0-THz double-drift region (DDR) impact avalanche transit time (IMPATT) diode based on wurtzite gallium nitride (Wz-GaN), due to the influence of parasitic series resistance, has been investigated. A two-dimensional (2-D) large-signal (L-S) simulation method based on a non-sinusoidal voltage excitation (NSVE) model has been used for this purpose. A comprehensive model of series resistance has been developed by considering the influence of skin effect, and the said model has been incorporated in the 2-D L-S simulation for studying the effect of RF power output and DC to RF conversion efficiency of the device. Results indicate 24.2-35.9% reduction in power output and efficiency due to the RF power dissipation in the positive series resistance. However, the device can still deliver 191.7-202.9 mW peak RF power to the load at 1.0 THz with 8.48-6.41% conversion efficiency. GaN IMPATT diodes are capable of generating higher RF power at around 1 THz than conventional diodes, but the effect of parasitic series resistance causes havoc reduction in power output and efficiency. The nature of the parasitic resistance is studied here in the level of device fabrication and optimization, which to our knowledge is not available at present. [ABSTRACT FROM AUTHOR]

An optimized two-step electrochemical deposition technique for the synthesis of a Cu2O/graphene platelet composite from copper acetate and a graphite rod is demonstrated. In the first step, graphene nanoplatelets were electrodeposited onto a stainless steel substrate from the graphite rod and then Cu2O NPs from copper acetate solution were electrodeposited onto the same electrode through the second electrodeposition step. Raman spectroscopy and X-ray photoelectron spectroscopy were performed to confirm the quality of the graphene nanoplatelets produced. X-ray diffraction studies revealed the successful formation of Cu2O nanoparticles. Transmission electron microscopy and field emission scanning electron microscopy were carried out to study the morphology, and the microscopic images revealed that the graphene surfaces were evenly anchored with Cu2O nanoparticles. The electrocatalytic behavior of the Cu2O/graphene platelet composite was analysed through cyclic voltammetry, differential pulse voltammetry and amperometric studies. The electrochemical studies revealed the utilization of the prepared material for non-enzymatic electrochemical sensing of H2O2. The amperometric studies showed the sensitivity and limit of detection of the prepared Cu2O/graphene platelet composite to be 52.8595 μA μM−1 cm−2 and 34.32 nM, respectively. [ABSTRACT FROM AUTHOR]

A new type of thin silicon-on-insulator (SOI) p-n junction photodiode (PD) with gold (Au) line-and-space grating gate electrode is proposed and demonstrated to have high quantum efficiency (QE) at visible wavelengths. This PD is similar to our previous one in the use of the grating and the metal–oxide–semiconductor structure but is very different in the use of the separate binary grating instead of the continuous one and the thick gate oxide. As a result, the diffracted light from the grating efficiently couples with the lateral propagation mode in the SOI slab waveguide, leading to an external QE one order of magnitude higher than that without the grating. In addition, the importance of the proper setting of the gate and substrate biases is shown so as to realize the wide depletion region and resultant high QE. [ABSTRACT FROM PUBLISHER]

A gold (Au) line and space (L/S) grating antenna for the silicon-on-insulator MOS (SOI–MOS) photodiode is investigated. The SOI–MOS photodiode has the advantages such as high-speed operation, large voltage gain per electric charge, and small dark current. However, its light sensitivity is usually very low due to the small volume of light absorption. In order to enhance the light sensitivity, a surface plasmon (SP) antenna is adopted. The SP antenna is constructed with a periodic metallic structure, and can convert the incident light to optical near-field around the surfaces of the antenna. By replacing the MOS gate with the SP antenna, it becomes possible to enhance the light absorption while keeping the advantages of SOI–MOS photodiode. This paper focuses on the visible light absorption in the SOI–MOS photodiode with the SP antenna. The structural conditions for high absorption efficiency and single-peaked spectroscopic characteristics, polarized light response, and resonance mechanisms are clarified by electromagnetic simulations using the finite-difference time-domain (FDTD) method. [ABSTRACT FROM PUBLISHER]

This paper presents a circuit design of a two-bit-per-cell Content-Addressable Memory (CAM) using Single-Electron Transistors (SETs). The key ideas of the proposed CAM architecture are (i) four-level data storage function implementing by a SET-based static memory cell and (ii) four-level data matching function employing periodic drain-current characteristics of SETs with dynamic phase-shift control. A simple multi-gate SET can be used to realize four-level data matching within a compact CAM cell circuit. As a result, the proposed two-bit-per-cell CAM architecture reduces both the number of transistors and the cell area to 1/3 compared with the conventional CAM architecture. [ABSTRACT FROM AUTHOR]

Devices that combine single-electron and metaloxide-semiconductor (MOS) transistors are newly proposed as basic components of multiple-valued (MV) logic, such as a universal literal gate and a quantizer. We verified their operation using single-electron and MOS transistors fabricated on the same wafer by pattern-dependent oxidation of silicon. We also discuss their application to an analog-to-digital converter, a MV adder, and MV static random-access memory. [ABSTRACT FROM AUTHOR]

Analytical model for asymmetric single-electron tunneling transistors (SETTs), in which resistance and capacitance parameters of source/drain junctions are not equal, has been developed. The model is based on the steady-state master equation, takes only the two most-probable charging states into account, and is therefore very simple. Even so, it can accurately reproduce the peculiar behaviors of an asymmetric SETT, such as the skew in the drain current-gate voltage characteristics and the Coulomb staircase in the drain current-drain voltage characteristic. Analytical expressions for the charge in the Coulomb island and the capacitance components of the SETT are also derived according to the same scheme, and it is demonstrated that the model can precisely describe the various aspects of the SETT behavior. [ABSTRACT FROM AUTHOR]

Reports on the application of a copper metallization process to quarter-micron complementary metal-oxide semiconductors (CMOS) using copper chemical vapor deposition (CVD) and chemical mechanical polishing (CMP). Evaluation of the metallization process; Electrical characteristics of the CMOS devices.

The sensitivity of silicon-on-insulator (SOI) lateral p-n junction photodiode was enhanced by attaching gold (Au) nanoparticles. This was confirmed by comparing I-V characteristics with and without Au nanoparticles at various substrate voltages. Twofold enhancement was attained in the visible wavelength region when the substrate was biased to positive. The substrate bias changed the area of depletion layer in SOI, and the light scattering by Au nanoparticles effectively enhanced the sensitivity when the area of depletion layer was small. [ABSTRACT FROM AUTHOR]

We report electron transport measurements of a silicon double dot formed in multigated metal-oxide-semiconductor structures with a 15-nm-thick silicon-on-insulator layer. Tunable tunnel coupling enables us to observe an excitation spectrum in weakly coupled dots and an energy level anticrossing in strongly coupled ones. Such a quantum dot molecule with both charge and energy quantization provides the essential prerequisite for future implementation of silicon-based quantum computations. [ABSTRACT FROM AUTHOR]

The problem of charge offset drift in single-electron tunneling (SET) devices can preclude their useful application in metrology and integrated devices. We demonstrate that in tunable-barrier Si-based SET transistors there is excellent stability, with a drift that is in general less than 0.01e; these devices exhibit some unwanted sensitivity to external perturbations including temperature excursions. Finally, we show that these devices can be “trained” to minimize their sensitivity to abrupt voltage changes. [ABSTRACT FROM AUTHOR]

On-chip all-optical switching based on the carrier plasma dispersion in an argon ion (Ar+) implanted photonic crystal (PhC) nanocavity that is connected to input/output waveguides is described. A high dose of Ar+ is introduced, and annealing is used to recrystallize the silicon and thus create dislocation loops at the center of the PhC slab. Dislocation loops enable the fast recombination of the carriers, which allows a fast switching recovery time for PhC switches. The switching window (∼70 ps) is three times smaller than that without ion implantation, while the required operating energy remains almost the same (<100 fJ). [ABSTRACT FROM AUTHOR]

Low current leakage characteristics of a novel silicon-on-insulator (SOI) device are investigated in view of application to a gain-cell dynamic random access memory (DRAM). The device consists of a two-layered poly-Si gate. Since, in this device, the memory node is electrically formed by the gate in undoped SOI wire, no p-n junction is required. The retention is found to be dominated by the subthreshold leakage, which leads to long data retention. The device also achieved a fast (10 ns) writing time and its fabrication process is compatible with those of SOI MOSFETs. The present results, thus, strongly suggest a way of conducting a gain-cell DRAM to be embedded into logic circuits. [ABSTRACT FROM AUTHOR]

We present a pixel-level angle sensitive detector composed of silicon-on-insulator (SOI) photodiode (PD) stacked with a gold surface plasmon (SP) antenna to affect the direction of the incoming light. The surface plasmons are excited in the grating-type SP antenna and enhance the diffraction efficiency of the grating. The diffracted light is coupled strongly with the propagation light in the SOI waveguide when the phase matching condition is satisfied. The phase matching takes place at a specific angle of light incidence, and the discrimination of the light based on the incident angle is achieved. As spatial patterns in the polar coordinate of the elevation-azimuth angles (θ, ϕ) of the incident light, we present the phase matching condition theoretically, the absorption efficiency in the SOI by simulation, and also the quantum efficiency of the SOI PD experimentally for different SP antennas of one-dimensional (1D) line-and-space (L/S) and two-dimensional (2D) hole array gratings under various polarization angles. 1D grating offers a polarization sensitive angle detection and 2D grating exhibits angle detection in two orthogonal directions, enabling a polarization independent angle sensitivity. A good agreement among the theory, simulation, and experiment are attained. The proposed device features relatively high quantum efficiency as an angle-sensitive pixel (ASP) and gives wider opportunities in applications such as three-dimensional (3D) imaging, depth-of-field extension, and lensless imaging. [ABSTRACT FROM AUTHOR]

Assuming that the 0.6-μm silicon-on-insulator (SOI) complementary metal–oxide–semiconductor (CMOS) technology, different Si-based temperature sensors such as metal-oxide-semiconductor field-effect transistor (MOSFET) (n-channel and p-channel), pn-junction diode (with p-body doping and without doping), and resistors (n+ or p+ single crystalline Si and n+ polycrystalline Si) were designed and characterized for its possible use in 1-THz antenna-coupled bolometers. The use of a half-wave dipole antenna connected to the heater end was assumed, which limited the integrated temperature sensor/heater area to be 15 × 15 µm. Our main focus was to evaluate the performances of the temperature sensor/heater part, and the optical coupling between the incident light and heater via an antenna was not included in the evaluation. The electrothermal feedback (ETF) effect due to the bias current was considered in the performance estimation. A comparative analysis of various SOI bolometers revealed the largest responsivity (Rv) of 5.16 kV/W for the n-channel MOSFET bolometer although the negative ETF in MOSFET reduced the Rv. The noise measurement of the n-channel MOSFET showed the NEP of 245 pW/Hz1/2, which was more than one order of magnitude smaller than that of the n+ polycrystalline Si resistive bolometer (6.59 nW/Hz1/2). The present result suggests that the n-channel MOSFET can be a promising detector for THz applications. [ABSTRACT FROM AUTHOR]

Using a device resembling a nano-charge-coupled-device and measuring the Coulomb blockade, we show how the Coulomb blockade degrades with increasing barrier conductance. To explain this behavior, we identify a new parameter, the “barrier capacitance.” This parameter can be used to elucidate information about the energy barrier under a gate with a size of a few tens of nanometers. [ABSTRACT FROM AUTHOR]

A single-electron-based circuit, in which electrons are transferred one by one with a turnstile and subsequently detected with a high-charge-sensitivity electrometer, was fabricated on a silicon-on-insulator substrate. The turnstile, which is operated by opening and closing two metal-oxide-semiconductor field-effect transistors alternately, allows single-electron transfer at room temperature owing to electric-field-assisted shrinkage of the single-electron box. It also achieves fast single-electron transfer (less than 10 ns) and extremely long retention (more than 104 s). We have applied these features to a multilevel memory and a time-division weighted sum circuit for a digital-to-analog converter. [ABSTRACT FROM AUTHOR]

We have achieved the operation of single-electron tunneling (SET) transistors with gate-induced electrostatic barriers using silicon nanowire metal-oxide-semiconductor field-effect transistor (MOSFET) structures. The conductance of tunnel barriers is tunable by more than three orders of magnitude. By using the flexible control of the tunable barriers, the systematic evolution from a single charge island to double islands was clearly observed. We obtained excellent reproducibility in the gate capacitances: values on the order of 10 aF, with the variation smaller than 1 aF. This flexibility and controllability both demonstrate that the device is highly designable to build a variety of SET devices based on complementary metal-oxide-semiconductor technology. [ABSTRACT FROM AUTHOR]

A multilevel dynamic random-access memory using a single-electron box (SEB) and single-electron transistor (SET) is fabricated on a silicon-on-insulator substrate. A one-dimensional field-effect transistor (FET), which is connected to the SEB, modulates a barrier potential to precisely control the number of electrons one by one in the SEB by means of the Coulomb-blockade phenomenon. At room temperature and 26 K, we demonstrate a multilevel memory, in which each interval between the levels is given by a single electron, by using the SET electrometer coupled capacitively to the SEB. The control of stored electrons by the FET assures long-retention time and high-speed write/erase operation. [ABSTRACT FROM AUTHOR]

Automatic phase control of the Coulomb-blockade (CB) oscillation of a single-electron transistor (SET) is proposed and experimentally demonstrated. Charges in the memory node (MN) capacitively coupled to the SET control the phase of the CB oscillation. The output signal of the SET can controls chares in the MN. This feedback mechanism automatically adjusts the amount of charges, so that the output signal is leveled with a requested one for arbitrary input signal of the SET. The electrical phase control realizes the demonstration of a multifunctional Boolean logic. Index Terms—Multifunctional logic; phase control; silicon; single-electron transistor. [ABSTRACT FROM AUTHOR]

A multipeak negative-differential-resistance device is proposed. The device comprises a single-electron transistor (SET) and a metal–oxide–semiconductor field-effect transistor (MOSFET), and can, in principle, generate an infinite number of current peaks. Operation of the proposed device is verified at 27 K with a SET fabricated by the pattern-dependent oxidation process and a MOSFET on the same silicon-on-insulator wafer. Six current peaks and a peak-to-valley current ratio of 2.1 are obtained, and multiple-valued memory operation is successfully demonstrated. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Examines the electrical properties of metal-insulator-semiconductor diodes fabricated from laser ablated YBa[sub 2]Cu[sub 3]O[sub 7-delta]/yttria stabilized zirconia films on silicon substrates. Usage of pulsed laser deposition; Leakage current measurements; Detection of mobile ions in the interface.