Showing papers on "Biasing published in 2013"
TL;DR: It is demonstrated that a p-n heterojunction diode based on atomically thin MoS2 and sorted semiconducting carbon nanotubes yields unprecedented gate tunability in both its electrical and optical properties, which is not observed in the case of bulk semiconductor devices.
Abstract: The p-n junction diode and field-effect transistor are the two most ubiquitous building blocks of modern electronics and optoelectronics. In recent years, the emergence of reduced dimensionality materials has suggested that these components can be scaled down to atomic thicknesses. Although high-performance field-effect devices have been achieved from monolayered materials and their heterostructures, a p-n heterojunction diode derived from ultrathin materials is notably absent and constrains the fabrication of complex electronic and optoelectronic circuits. Here we demonstrate a gate-tunable p-n heterojunction diode using semiconducting single-walled carbon nanotubes (SWCNTs) and single-layer molybdenum disulfide as p-type and n-type semiconductors, respectively. The vertical stacking of these two direct band gap semiconductors forms a heterojunction with electrical characteristics that can be tuned with an applied gate bias to achieve a wide range of charge transport behavior ranging from insulating to rectifying with forward-to-reverse bias current ratios exceeding 10(4). This heterojunction diode also responds strongly to optical irradiation with an external quantum efficiency of 25% and fast photoresponse <15 μs. Because SWCNTs have a diverse range of electrical properties as a function of chirality and an increasing number of atomically thin 2D nanomaterials are being isolated, the gate-tunable p-n heterojunction concept presented here should be widely generalizable to realize diverse ultrathin, high-performance electronics and optoelectronics.
389 citations
TL;DR: In this paper, a review of terahertz-emission devices based on the high-temperature superconductor Bi2Sr2CaCu2O8+δ is presented.
Abstract: Layered superconductors such as the copper-oxide high-temperature superconductor Bi2Sr2CaCu2O8+δ are emerging as compact sources of coherent continuous-wave electromagnetic radiation in the subterahertz and terahertz frequency ranges. The basis of their operation is the Josephson effect, which intrinsically occurs between the superconducting layers. The Josephson effect naturally converts a direct-current voltage into a high-frequency electric current. Therefore, a unique property of the devices reviewed here is the wide tunability of their frequency by varying the bias voltage. Recently, emission powers of free-space radiation of several hundreds of microwatts and emission linewidths as low as 6 MHz at 600 GHz have been achieved. These devices are promising for new applications in imaging, medical diagnostics, spectroscopy and security. Recent progress on terahertz-emission devices based on the high-temperature superconductor Bi2Sr2CaCu2O8+δ is reviewed. The emission mechanism is explained as a result of collective resonant modes in a stack of intrinsic Josephson junctions. Remarkable features of the linewidth, tunability, the optimum bias condition and the thermal influence are discussed.
247 citations
TL;DR: A two-terminal memristor memory based on a single VO2 nanowire is reported that can not only provide switchable resistances in a large range of about four orders of magnitude but can also maintain the resistances by a low bias voltage.
Abstract: A two-terminal memristor memory based on a single VO2 nanowire is reported that can not only provide switchable resistances in a large range of about four orders of magnitude but can also maintain the resistances by a low bias voltage. The phase transition of the single VO2 nanowire was driven by the bias voltage of 0.34 V without using any heat source. The memristive behavior of the single VO2 nanowire was confirmed by observing the switching and non-volatile properties of resistances when voltage pulses and low bias voltage were applied, respectively. Furthermore, multiple retainable resistances in a large range of about four orders of magnitude can be utilized by controlling the number and the amount of voltage pulses under the low bias voltage. This is a key step towards the development of new low-power and two-terminal memory devices for next-generation non-volatile memories.
125 citations
TL;DR: The mechanically controlled break-junction technique is used to measure electronic transport through a single-molecule junction containing two coupled spin centres that are confined on two Co(2+) ions and can be used to switch between two states of the molecule.
Abstract: A bias voltage can be used to reversibly switch between the two states of a coupled spin pair in a single magnetic molecule.
102 citations
TL;DR: The conduction properties of graphene were tuned by tailoring the lattice by using an accelerated helium ion beam to embed low-density defects in the lattices to suggest that conduction tuning is possible through strong localization of carriers at sites induced by a sparsely distributed random potential modulation.
Abstract: The conduction properties of graphene were tuned by tailoring the lattice by using an accelerated helium ion beam to embed low-density defects in the lattice. The density of the embedded defects was estimated to be 2–3 orders of magnitude lower than that of carbon atoms, and they functionalized a graphene sheet in a more stable manner than chemical surface modifications can do. Current modulation through back gate biasing was demonstrated at room temperature with a current on–off ratio of 2 orders of magnitude, and the activation energy of the thermally activated transport regime was evaluated. The exponential dependence of the current on the length of the functionalized region in graphene suggested that conduction tuning is possible through strong localization of carriers at sites induced by a sparsely distributed random potential modulation.
88 citations
TL;DR: In this article, the effects of substrate bias voltages on the ion energy and the ion flux were investigated for Al2O3, Co3O4, and TiO2 thin films, and it was found that these process and material properties can be tailored using substrate biasing.
Abstract: Two substrate-biasing techniques, i.e., substrate-tuned biasing and RF biasing, have been implemented in a remote plasma configuration, enabling control of the ion energy during plasma-assisted atomic layer deposition (ALD). With both techniques, substrate bias voltages up to −200 V have been reached, which allowed for ion energies up to 272 eV. Besides the bias voltage, the ion energy and the ion flux, also the electron temperature, the electron density, and the optical emission of the plasma have been measured. The effects of substrate biasing during plasma-assisted ALD have been investigated for Al2O3, Co3O4, and TiO2 thin films. The growth per cycle, the mass density, and the crystallinity have been investigated, and it was found that these process and material properties can be tailored using substrate biasing. Additionally, the residual stress in substrates coated with Al2O3 films varied with the substrate bias voltage. The results reported in this article demonstrate that substrate biasing is a promising technique to tailor the material properties of thin films synthesized by plasma-assisted ALD.
85 citations
TL;DR: In this paper, a thin layer of sol-gel grown nanocrystalline p-type TiO 2 was deposited on a thermally oxidized p-Si (2 −5 cm resistivity and (1 −0 −0) orientation) substrate, which was characterized by X-ray diffraction and field emission scanning electron microscopy (FESEM).
Abstract: A thin layer (~1 μm) of sol–gel grown nanocrystalline p-type TiO 2 was deposited on a thermally oxidized p-Si (2–5 Ω cm resistivity and (1 0 0) orientation) substrate. The surface was characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM), which also confirmed the nanocrystallinity of the material. Optical absorption spectroscopy was carried out to calculate the band gap of the material. Two lateral Pd contacts were used as the catalytic metal electrodes on TiO 2 to fabricate the resistive gas sensor for hydrogen sensing. Detail gas response characteristics, selectivity and the stability of the sensor structure were studied. The sensors showed high response (~55%) to hydrogen with an appreciable short response time of 2 s at the optimized temperature, 175 °C and biasing voltage, 0.1 V in a steady dynamic atmosphere of 1% H 2 with N 2 as carrier gas. For practical applications, similar set of sensor experiments was also performed in air ambient. At 100 °C and 1.0 V bias the response magnitude was reduced to 49% but the response time came down to 1.3 s. The recovery time was lowest (~34 s) at 150 °C. The reduction in the recovery time in air is possibly due to quick removal of residual hydrogen from the surface of the sensor by interaction with oxygen present in air. The sensors showed selectivity to hydrogen and good stability. There was no degradation after working for 42 h in a discrete mode (6 h/day) in nitrogen and also in air. A possible gas sensing mechanism was suggested with a qualitative energy band diagram.
85 citations
TL;DR: In this paper, single-crystalline V/Fe(0.7nm)/MgO(1.2nm)/Fe(20 nm) magnetic tunnel junctions are studied to quantify the influence of an electric field on the Fe/mgO interface magnetic anisotropy.
Abstract: Single-crystalline V/Fe(0.7 nm)/MgO(1.2nm)/Fe(20 nm) magnetic tunnel junctions are studied to quantify the influence of an electric field on the Fe/MgO interface magnetic anisotropy. The thinnest Fe soft layer has a perpendicular magnetic anisotropy (PMA), whereas the thickest Fe layer acts as sensor for magnetic anisotropy changes. When electrons are added at the PMA Fe/MgO interface (negative voltage), no anisotropy changes are observed. For positive voltage, the anisotropy constant decreases with increasing bias voltage. A huge 1150 fJ V−1 m−1 anisotropy variation with field is observed and the magnetization is found to turn from out-of-plane to in-plane of the sample with the applied voltage.
85 citations
TL;DR: It is observed that variations of the photocurrent with bias voltage depend strongly on the n-type doping in GaN nanowires in both electrolytes, which are analyzed in the context of GaN surface band bending and its variation with the incorporation of Si-doping.
Abstract: We have studied the photoelectrochemical properties of both undoped and Si-doped GaN nanowire arrays in 1 mol l 1 solutions of hydrogen bromide and potassium bromide, which were used separately as electrolytes. It is observed that variations of the photocurrent with bias voltage depend strongly on the n-type doping in GaN nanowires in both electrolytes, which are analyzed in the context of GaN surface band bending and its variation with the incorporation of Si-doping. Maximum incident-photon-to-current-conversion efficiencies of 15% and 18% are measured for undoped and Si-doped GaN nanowires under 350 nm light illumination, respectively. Stable hydrogen generation is also observed at a zero bias potential versus the counter-electrode. (Some figures may appear in colour only in the online journal)
84 citations
TL;DR: In this article, the spin transport properties of molecular devices constructed by hydrogen-phthalocyanine and transition metal (TM)phthalocynine molecule with zigzag graphene nanoribbon electrodes are investigated by the Keldysh nonequilibrium Green's function method in combination with the density functional theory.
70 citations
TL;DR: In this paper, the influence of the bias voltage on emission properties of a red emitting InP/GaInP quantum dot based single-photon source was investigated under pulsed electrical excitation, where the applied bias voltage can influence the band bending of the p-i-n diode and thus the charge carrier escape by quantum tunneling.
Abstract: The influence of the bias voltage on emission properties of a red emitting InP/GaInP quantum dot based single-photon source was investigated. Under pulsed electrical excitation, we can influence the band bending of the p-i-n diode with the applied bias voltage and thus the charge carrier escape by quantum tunneling. This leads to control over the non-radiative decay channel and allows carrier escape times as low as 40 ps, effectively reducing the time jitter of the photon emission. We realized high excitation repetition rates of up to 2 GHz while autocorrelation measurements with g(2)(0)-values of 0.27 attest dominant single-photon emission.
TL;DR: An output capacitor-free low-dropout regulator (LDO) using a class-AB operational amplifier and an assistant push–pull output stage (APPOS) circuit to enable fast-transient response with ultralow-power dissipation is presented in this brief.
Abstract: An output capacitor-free low-dropout regulator (LDO) using a class-AB operational amplifier and an assistant push–pull output stage (APPOS) circuit to enable fast-transient response with ultralow-power dissipation is presented in this brief. The APPOS circuit is proposed to deliver an extra current that is directly proportional to the output current of the class-AB operational amplifier during transient state with an automatic on/off feature. Moreover, the small-signal and large-signal responses of LDO can be separately optimized. As a result, transient performances of LDO are improved significantly without requiring an area-consuming on-chip capacitor anymore. The proposed LDO has been implemented in a standard 0.35- $\mu\hbox{m}$ CMOS process. Experimental results show that the LDO can regulate the output voltage at 1.0 V from a 1.2-V supply voltage for the maximum load current of 100 mA. The output voltage fully recovers within 2.7 $\mu\hbox{s}$ with the load current switching from 100 $\mu\hbox{A}$ to 100 mA at a 1.2- $\mu\hbox{A}$ quiescent current.
TL;DR: In this paper, a modified mesa structure of high-Tc superconducting Bi2Sr2CaCu2O8+δ with a thin underlaying base superconductor (∼3 μm), the effective working temperature of the continuous and monochromatic terahertz emitter is extended up to 70
Abstract: Using a modified mesa structure of high-Tc superconducting Bi2Sr2CaCu2O8+δ with a thin underlaying base superconductor (∼3 μm), the effective working temperature of the continuous and monochromatic terahertz emitter is extended up to 70 K, and the maximum power of ∼30 μW at 0.44 THz is achieved at the relatively high temperature of Tb = 55 K in a low bias current retrapping region. The diverging behavior of the intensity occurring at 55 K in the low current regime without hot spot formation may provide us an important clue for the stronger THz radiation from intrinsic Josephson junction devices.
TL;DR: In this paper, a semiconductor-based resistive switching nonvolatile memory devices with graphene oxide (GO) as an active layer which is sandwiched between aluminum (Al) metal and semiconductors such as Si and Ge was reported.
TL;DR: In this paper, the relationship between one of deposition parameter, negative substrate bias voltages Vs (10 −V −300 −V), and the coatings characterization such as microhardness, stress, adhesion of the coating, elastic strain to failure related to H/E ratio were investigated.
TL;DR: In this paper, the effect of voltage on the perpendicular magnetic anisotropy in an ultrathin Fe80B20 layer sandwiched between two MgO barrier layers with different thicknesses was investigated.
Abstract: We investigated the effect of voltage on the perpendicular magnetic anisotropy in an ultrathin Fe80B20 layer sandwiched between two MgO barrier layers with different thicknesses, in which the bias voltage is predominantly applied to one of the MgO layers. The application of both positive and negative bias voltages enhanced the perpendicular anisotropy, in contrast with the odd function dependence previously observed in a MgO/ferromagnetic metal/non-magnetic metal structure. Moreover, for positive bias voltages, the large anisotropy change slope of 108 fJ/Vm was demonstrated. These results indicate that the MgO-sandwich structure has high potential to extend the availability of the voltage effect.
TL;DR: It is shown that operating bias condition has a significant role in device reliability by altering value and location of the peak temperature, which then alters the type and rate of thermally induced degradation taking place at critical locations such as the drain side corner of the gate.
TL;DR: In this article, a millimeter-wave phase shifter based on a CMOS slow-wave coplanar-waveguide transmission-line topology is presented, where a liquid crystal (LC) material is used as a tunable dielectric between the signal strip and the shielding plane of the slowwave transmission line.
Abstract: Based on a CMOS slow-wave coplanar-waveguide transmission-line topology, a novel compact millimeter-wave phase shifter is presented. The tunability is accomplished by using a liquid crystal (LC) material as a tunable dielectric between the coplanar signal strip and the shielding plane of the slow-wave transmission line. The device tunability is considerably enhanced by moving the free-standing signal strip with the application of a bias voltage. Combining the miniaturizing benefits of the slow-wave effect with the continuous tuning of LC material, the proposed device occupies only 0.38 mm2 and exhibits high performance. The phase shifter was characterized up to 45 GHz for a maximum bias voltage of 20 V without significant power consumption. The reproducible measurements show a figure-of-merit (ratio between the maximum phase shift and the maximum insertion loss) of 51°/dB at 45 GHz.
Patent•
14 Mar 2013TL;DR: In this paper, a method for determining an operating bias voltage of a photodiode is presented. But the method is not suitable for the case of light detection and ranging (LIDAR) systems.
Abstract: Methods and devices are provided for determining an operating bias voltage of a photodiode. One example method includes (i) varying a bias voltage of a photodiode; (ii) detecting spurious signals generated by the photodiode while varying the bias voltage of the photodiode; (iii) determining a threshold bias voltage at which a frequency of occurrence of the spurious signals reaches a threshold frequency; (iv) determining an operating bias voltage for the photodiode based on at least the threshold bias voltage; and (v) operating the photodiode with the operating bias voltage in a light-detection and ranging (LIDAR) system.
TL;DR: In this paper, the double graphene-layer (GL) structures with the resonant-tunneling (RT) and the negative differential inter-GL conductivity were studied. And the results showed that the electron-hole plasma in the double-GL RT structures with realistic parameters is stable with respect to the self-excitation of plasma oscillations and aperiodic perturbations.
Abstract: We study the dynamic effects in the double graphene-layer (GL) structures with the resonant-tunneling (RT) and the negative differential inter-GL conductivity. Using the developed model, which accounts for the excitation of self-consistent oscillations of the electron and hole densities and the ac electric field between GLs (plasma oscillations),
we calculate the admittance of the double-GL RT structures as a function of the signal frequency and applied voltages, and the spectrum and increment/decrement of plasma oscillations. Our results show that the electron-hole plasma in the double-GL RT structures with realistic parameters is stable with respect to the self-excitation of plasma oscillations and aperiodic perturbations. The stability of the electron-hole plasma at the bias voltages corresponding to the inter-GL RT and strong nonlinearity of the RT current-voltage characteristics enable using the double-GL RT structures for detection of teraherz (THz) radiation. The excitation of plasma oscillations by the incoming THz radiation can result in a sharp resonant dependence of detector responsivity on radiation frequency and the bias voltage. Due to a strong nonlinearity of the current-voltage characteristics of the double-GL structures at RT and the resonant excitation of plasma oscillations, the maximum responsivity, $R_V^{max}$, can markedly exceed the values $(10^4 - 10^5)$~V/W at room temperature.
TL;DR: In this paper, a graphene sheet gated with a ridged ground plane, creating a soft-boundary (SB) graphene nanoribbon, is considered and two types of modes are found; fundemental and higher-order modes with no apparent cutoff frequency and with energy distributed over the created channel, and edge modes with energy concen-trated at the softboundary edge.
Abstract: A graphene sheet gated with a ridged ground plane, creating a soft-boundary (SB) graphene nanoribbon, is considered. By adjusting the ridge parameters and bias voltage a channel can be created on the graphene which can guide TM surface plasmon polaritons (SPP). Two types of modes are found; fundemental and higher-order modes with no apparent cutoff frequency and with energy distributed over the created channel, and edge modes with energy concen-trated at the soft-boundary edge. Dispersion curves, electric near-field patterns, and current distributions of these modes are determined. Since the location where energy is concentrated in the edge modes can be easily controlled electronically by the bias voltage and frequency, the edge-mode phenomena is used to propose a novel voltage controlled plasmonic switch and a plasmonic frequency demultiplexer.
TL;DR: In this article, the capacitance voltage measurements demonstrate that accumulation, depletion, and deep depletion regimes can be controlled by the bias voltage, opening the route for diamond metal-oxide-semiconductor field effect transistor.
Abstract: Metal-oxide-semiconductor structures with aluminum oxide as insulator and p-type (100) mono-crystalline diamond as semiconductor have been fabricated and investigated by capacitance versus voltage and current versus voltage measurements. The aluminum oxide dielectric was deposited using low temperature atomic layer deposition on an oxygenated diamond surface. The capacitance voltage measurements demonstrate that accumulation, depletion, and deep depletion regimes can be controlled by the bias voltage, opening the route for diamond metal-oxide-semiconductor field effect transistor. A band diagram is proposed and discussed.
TL;DR: In this article, the temperature distribution at the surface of BSCCO stacks utilizing the temperature-dependent 612nm fluorescence line of Eu3+ in a europium chelate was investigated.
Abstract: Stacks of intrinsic Josephson junctions (IJJs) made from high-temperature superconductors such as Bi2Sr2CaCu2O8+δ (Bi-2212) (BSCCO) are a promising source of coherent continuous-wave terahertz radiation. It is thought that at electrical bias conditions under which THz-emission occurs, hot spots may form due to resistive self-heating, and that these spots may be highly beneficial for the generation of high levels of THz power. Here, we perform an imaging study of the temperature distribution at the surface of BSCCO stacks utilizing the temperature-dependent 612 nm fluorescence line of Eu3+ in a europium chelate. The images directly reveal a highly non-uniform temperature distribution in which the temperature in the middle of the stack can exceed the superconducting transition temperature by tens of Kelvin under biasing conditions typical for THz-emission.
TL;DR: In this paper, the performance of silicone rubber composites containing 0, 10 and 30 wt % loading of silica filler is investigated in the initial-tracking voltage test method of the inclined plane test under AC and DC showing the most inferior erosion class under +DC followed by -DC and then AC.
Abstract: In this paper, the performance of silicone rubber composites containing 0, 10 and 30 wt % loading of silica filler is investigated in the initial-tracking voltage test method of the inclined plane test under AC and DC showing the most inferior erosion class under +DC followed by -DC and then AC. DC as compared to AC dry-band arcing characteristics are analyzed by conducting leakage current measurements prior to and after the inception of dry-band arcing. At high test voltages, instability of the contaminant rivulet is found to be an important factor in the development of dry band arcing and, consequently, biasing the test outcomes when equal voltages of rms AC and DC are selected. The initial tracking voltage in ASTM D2303 is, therefore, proposed as a reliable approach by which +DC and -DC test voltages can be reliably selected. A coefficient of variation parameter is also proposed as a useful mean of selecting the equivalent DC voltages, and the validity of the parameter is verified experimentally using the initialtracking voltage test method. Erosion in the constant voltage method is investigated under DC by applying the equivalent voltages and compared to AC. Based on this methodology, it is suggested that an improvement in silicone rubber compositions is needed for DC. Moreover, the need to select the creepage distance of polymer insulators designed for AC, yet to be used under DC, with reference to tracking/erosion performance is highlighted.
TL;DR: In this paper, a low-energy consumption rapid single-fluxquantum (RSFQ) circuit was proposed, where bias currents were fed to Josephson junctions from lowered constant voltages through small resistors without extra inductors.
Abstract: We report successful operations of low-energy consumption rapid single-flux-quantum (RSFQ) circuits applying lowered driving voltages, called LV-RSFQ, using different fabrication processes. In the LV-RSFQ, we feed bias currents to Josephson junctions from lowered constant voltages (less than 1 mV) through small resistors without extra inductors. Both static and dynamic energy consumption are reduced because of suppression of amplitudes of SFQ pulses, in exchange for slower switching speed. We show that the switching speed in LV-RSFQ circuits is improved by increasing critical current density of Josephson junctions. We demonstrated high-speed operations of LV-RSFQ shift registers in a range of 5-40 GHz and 15-90 GHz using the 2.5-kA/cm2 and 10-kA/cm2 fabrication technologies, respectively. Comparison of the experimental results of the LV-RSFQ circuits fabricated using two different technologies derives the optimum bias voltage in terms of energy-delay product ranged from 0.1 to 1.0 ICRS, where ICRS is the product of Josephson critical current and shunt resistance.
TL;DR: It is experimentally demonstrated that SiC high voltage Power MOSFTEs exhibit an unstable electro-thermal behavior for given electrical conditions, depending on the chip thermal impedance, which can lead to hot-spot formation and eventually thermal runaway whit subsequent device destruction after a stressful short-circuit.
TL;DR: In this paper, a high reliability offset-tolerant sensing circuit for deep submicron spin transfer torque magnetic tunnel junction (STT-MTJ) memory is presented, which is able to tolerate the increased process variations as technology scales down to the deep sub-micron nodes.
Abstract: A high reliability offset-tolerant sensing circuit is presented for deep submicron spin transfer torque magnetic tunnel junction (STT-MTJ) memory. This circuit, using a triple-stage sensing operation, is able to tolerate the increased process variations as technology scales down to the deep submicron nodes, thus improving significantly the sensing margin. Meanwhile, it clamps the bit-line voltage to a predefined small bias voltage to avoid any read disturbance during the sensing operations. By using the STMicroelectronics CMOS 40 nm design kit and a precise STT-MTJ compact model, Monte Carlo simulations have been carried out to evaluate its sensing performance.
TL;DR: In this paper, the error-free operation of an all-Si ion-implanted CMOS-compatible waveguide p-i-n photodiode (PD) is experimentally demonstrated at 1.55 μm with 2.5 and 10 Gb/s data rates.
Abstract: The error-free operation of an all-Si ion-implanted CMOS-compatible waveguide p-i-n photodiode (PD) is experimentally demonstrated at 1.55 μm with 2.5 and 10 Gb/s data rates. Detector sensitivity as a function of bias voltage is measured for PDs of two different lengths, 250 μm and 3 mm. The photocurrent increase caused by bringing the PD into a highly absorbing state via forward biasing is also measured, and it is shown that a resulting 15 dB improvement in receiver sensitivity can be expected. The limiting factors of the device frequency response are analyzed, and the measured PDs are shown to have comparable dark currents, responsivities, and sensitivities to reported Ge PDs.
TL;DR: In this paper, a dual-band short/mid-wavelength infrared photodetector based on InAs/GaSb/AlSb type-II superlattice with designed cut-off wavelengths of 2μm and 4μm was demonstrated.
Abstract: High performance bias-selectable dual-band short-/mid-wavelength infrared photodetector based on InAs/GaSb/AlSb type-II superlattice with designed cut-off wavelengths of 2 μm and 4 μm was demonstrated. At 150 K, the short-wave channel exhibited a quantum efficiency of 55%, a dark current density of 1.0 × 10−9 A/cm2 at −50 mV bias voltage, providing an associated shot noise detectivity of 3.0 × 1013 Jones. The mid-wavelength channel exhibited a quantum efficiency of 33% and a dark current density of 2.6 × 10−5 A/cm2 at 300 mV bias voltage, resulting in a detectivity of 4.0 × 1011 Jones. The spectral cross-talk between the two channels was also discussed for further optimization.
TL;DR: In this article, the double graphene-layer (GL) structures with the resonant-tunnelling (RT) and the negative differential inter-GL conductivity were investigated for detecting teraherz (THz) radiation.
Abstract: We study the dynamic effects in the double graphene-layer (GL) structures with the resonant-tunnelling (RT) and the negative differential inter-GL conductivity. Using the developed model, which accounts for the excitation of self-consistent oscillations of the electron and hole densities and the ac electric field between GLs (plasma oscillations), we calculate the admittance of the double-GL RT structures as a function of the signal frequency and applied voltages, and the spectrum and increment/decrement of plasma oscillations. Our results show that the electron?hole plasma in the double-GL RT structures with realistic parameters is stable with respect to the self-excitation of plasma oscillations and aperiodic perturbations. The stability of the electron?hole plasma at the bias voltages corresponding to the inter-GL RT and strong nonlinearity of the RT current?voltage characteristics enable using the double-GL RT structures for detection of teraherz (THz) radiation. The excitation of plasma oscillations by the incoming THz radiation can result in a sharp resonant dependence of detector responsivity on radiation frequency and the bias voltage. Due to a strong nonlinearity of the current?voltage characteristics of the double-GL structures at RT and the resonant excitation of plasma oscillations, the maximum responsivity, , can markedly exceed the values (104?105)?V?W?1 at room temperature.