Graphene-based Detectors Research Articles

Temperature-dependent zero-field splittings in graphene

The topological bandgap of graphene induced by intrinsic spin-orbit coupling is so narrow that it was experimentally identified for the first time only in 2019. In this work, the authors use a specific electron spin resonance technique, based on photoconductivity measurements using graphene-based terahertz detectors, to probe zero-field splittings of graphene as a function of temperature. They demonstrate experimentally that the intrinsic spin-orbit coupling and the staggered sublattice potential, which reduces the topological gap, are both temperature dependent.

Optimization of terahertz detectors based on graphene field effect transistors by high impedance antennae

This contribution presents the results of investigations performed on monolayer graphene field effect transistor- based (GFET-based) terahertz detectors. We have implemented three different types of planar antennae: a bowtie, a bow-tie with transmission lines and a slot-disc, allowing us to realize different conditions for high-frequency impedance matching. We present a semi-empirical model which uses physical parameters derived from electrical characterization results of devices and electrodynamic characteristics of antennae, allowing us to predict THz responsivity. Model predictions have been compared with the responsivity measurements performed at room temperature in a frequency range from 50 to 1250 GHz. Good agreement between the model predictions and experimental results implies the eligibility of a distributed resistive mixing approximation for GFET. In addition, the device stability, the temperature dependence and the origin of noise in the transistor channel have been investigated. Finally, to the best of our knowledge, we demonstrate the record performance values for room temperature graphene-based terahertz detectors: 80V/W optical responsivity without the normalization to the antenna effective area and a noise equivalent power of 111 pW/√Hz at 336 GHz.

Non-contact, low-cost regional greenhouse gases detection via 3D laminated graphene-based photoelectric construct

Although monitoring greenhouse gases (GHG) is of crucial significance in addressing global climate change, contemporary GHG measuring equipment is expensive, bulky, and installed in only a few areas, leading to several limitations for responding in real-time. Besides, there are difficulties in measuring atmospheric constitutions in living spaces due to problems caused by the detection method that is used in measuring devices and the limits of observation incurred by spatial and operational contingencies. Here, we report a graphene-based photoelectric detector that provides low-cost and high-precision monitoring of GHGs, irrespective of the contiguity of the gas to the sensor unit. The graphene photodetection materials, laminated under high temperature and pressure conditions, were designed as three-dimensional elements in order to optimally absorb light energy passed through the GHG layers. As a result, the photoelectric detector indicated accurate responsivity to 216 ppm of carbon dioxide, 0.06 ppm of carbon monoxide, and 0.88 ppm of mixed methane and carbon dioxide gas. Of greater interest, it showed a high responsivity of 45% when 12 μW/cm2 of incident light passed through 1.09 ppm of carbon monoxide atmosphere. Our study is at the cornerstone of building high-density GHG monitoring networks within cities and metropolitan areas.

Efficient mid-infrared wavelength converter based on plasmon-enhanced nonlinear response in graphene nanoribbons

Graphene plasmons with enhanced localized electric field have been used for boosting the light–matter interaction in linear optical nano-devices. Meanwhile, graphene is an excellent nonlinear material for several third-order nonlinear processes. We present a theoretical investigation of the mechanism of plasmon-enhanced third-order nonlinearity susceptibility of graphene nanoribbons. It is demonstrated that the third-order nonlinearity susceptibility of graphene nanoribbons with excited graphene surface plasmon polaritons can be an order of magnitude larger than the intrinsic susceptibility of a continuous graphene sheet. Combining these properties with the relaxed phase matching condition due to the ultrathin graphene, we propose a novel plasmon-enhanced mid-infrared (MIR) wavelength converter with arrays of graphene nanoribbons. The wavelength of signal light is in the MIR range, which can excite the tunable surface plasmons polaritons in arrays of graphene nanoribbons. The efficiency of the converter from MIR to near-infrared wavelength can be remarkably improved by 60 times compared with a graphene sheet without graphene plasmons. This work provides a novel idea for the efficient application of graphene in nonlinear optical nano-devices. The proposed MIR wavelength converter is compact, tunable and has promising potential in graphene-based MIR detectors with high detection efficiency.

Fermi-Surface Modulation of Graphene Synergistically Enhances the Open-Circuit Voltage and Quantum Efficiency of Photovoltaic Solar-Blind Ultraviolet Detectors.

Increasing the open-circuit voltage (VOC) is of a great significance to achieve high photoelectric conversion efficiency in photovoltaic applications. Here, we present a simple NO2 doping strategy that can significantly modulate the VOC of graphene-based solar-blind ultraviolet photodetectors from 0.96 to 1.84 V. The intriguing result can be demonstrated by the fact that NO2 doping lowers the Fermi surface of graphene and thus enhances quasi-Fermi level splitting of the whole device under illumination. The >103% increase of both external quantum efficiency and photoresponsivity compared to before doping is the result of a 0.88 V increase in the VOC. Our work sheds light on the forming mechanism of VOC in graphene-based photovoltaic detectors and further suggests alternative pathways to enhance the VOC of photovoltaic devices with high efficiency.

Broadband and Ultrasensitive Graphene-Based Mechanical Wave Detector with Nanosecond Response Used for Biological Photoacoustic Imaging.

Achieving broadband and sensitive mechanical wave detection with fast time response remains a great challenge. Here, we exploited the polarization-sensitive absorption characteristics and ultrafast photoelectric response of graphene to construct a broadband and ultrasensitive detector with a nanosecond response for mechanical wave detection. The unprecedented performance of the graphene-based detector allowed us to detect high-frequency mechanical waves over 100 MHz with a detection limit of 0.18 kPa. Moreover, we applied the detector in high-contrast photoacoustic imaging of human hairs and a mouse hindlimb to demonstrate its capability in detection of photoacoustic waves. This device could also find application in other areas such as THz detection and modulation.

Graphene-based detectors for directional dark matter detection

Dark matter detectors with directional sensitivity have the capability to distinguish dark matter induced nuclear recoils from isotropic backgrounds, thus providing a smoking gun signature for dark matter in the Galactic halo. Motivated by recent progress in graphene and two-dimensional materials research, we propose a novel class of directional dark matter detectors utilizing graphene-based van der Waals heterostructures. A conceptual design of the detector based on graphene/hexagonal boron nitride and graphene/molybdenum disulfide heterostructures is developed and analyzed. The proposed detector has modular scalability, keV-scale detection threshold, nanometer position resolution, sensitivity down to 10 mathrm {GeV}/c^2 dark matter mass, and intrinsic head-tail discrimination and background rejection capabilities.

Coherent Detection of Terahertz Radiation with Graphene

Despite that significant efforts have been made in the development of time-integrated graphene-based detectors operating in vis/IR/THz ranges, little is known about coherent detection of THz pulses...

A graphene-based neutral particle detector

A neutral particle detector is presented, in which the traditionally used target material, indium tin oxide (ITO), is replaced by graphene. The graphene-based detector enables collinear photodetachment measurements at a significantly shorter wavelength of light down to 230 nm compared to ITO-based detectors, which are limited at 335 nm. Moreover, the background signal from the photoelectric effect is drastically reduced when using graphene. The graphene based detector, reaching 1.7 eV further into the UV energy range, allows increased possibilities for photodetachment studies of negatively charged atoms, molecules, and clusters.

Surface plasmon polariton graphene midinfrared photodetector with multifrequency resonance

Midinfrared spectrum region has proved its great potential in various fields including security, medical examination, product inspection, and materials characterization. However, midinfrared detectors, one of the most important components, have not been fully developed and their performance can be much improved. In contrast to well-known nanostructured semiconductor detectors, graphene-based detectors are emerging and are proposed to tackle shortcomings of earlier detectors. Nevertheless, they still suffer from obstacles due to low light absorption originating from a single atomic layer. Recently, the introduction of plasmonic antennas is changing the situation and is attracting much interest. We present a midinfrared photodetector based on a multiresonant frequency bull’s eye antenna coupled with monolayer graphene. The bull’s eye antenna is one of the plasmonic antennas that can achieve high concentration of electric field and enhanced transmission of incident light. Though conventional bull’s eye antennas exhibit only single resonant frequency that restricts to a measured frequency range, we here designed and fabricated the bull’s eye antenna with wider band transmission so that various frequency regions can be studied with a single device. We demonstrated that the graphene device integrated with the multifrequency plasmonic antenna enabled the room-temperature midinfrared detection, together with the ability of frequency filtering in a desirable band. Our device design is also applicable to other frequency regions including visible light and terahertz waves by adjusting structural parameters.

Infrared photodetectors based on graphene metal nano clusters

Graphene is an outstanding photoconductive material for photodetection because of its wide range absorption spectrum and ultrafast response. It is well understood that by adding metal nanoparticle clusters on graphene layer enhances the absorption, also makes possible to focus on a particular region of the optical spectra via subwavelength plasmonic resonances between nanocluster and graphene substrate.In this article, we have designed an improved structure for gold nonamer nanodisk arrays on graphene as a photodetector to enhance the light absorption for optical communication spectrum. Effects of different structural parameters on absorption spectrum have been investigated, numerically. We have shown that light absorption in graphene-based detectors can be manipulated by tuning cluster size, thickness, inter disks gap distance, graphene position, and the number of graphene layers. By changing the radius of central and peripheral disks, we have shown that the Au nonamer on top of graphene is able to support strong sub- and superradiant plasmon resonances because of its unique geometrical features and a second absorption peak is generated. This additionally generated absorption peak is more suitable for application in 1550 nm nanostructure photodetectors.

Graphene-based broadband terahertz detector integrated with a square-spiral antenna.

Raising interest in terahertz radiation (loosely defined as the 0.1∼10 THz frequency range) for the application-oriented issues in everyday life requires progressive development of fast, sensitive, and portable photodetectors. In this Letter, a broadband graphene-based terahertz detector with good integrability and sensitivity at room temperature is proposed. It is based on the chemical vapor deposited-grown graphene integrated with a square-spiral metal antenna which, on one hand, improves the efficiency for electromagnetic coupling and, on the other hand, facilitates the hot-electron photo-thermoelectric process for photodetection. Sensitivity over 28V/W at room temperature and noise-equivalent power of less than 0.35 nW/Hz0.5 are demonstrated in reference to the incident power. The presented results appealingly open an alternative way to realize chip-level graphene-based terahertz optoelectronics with good scalability and expected performance for targeted terahertz applications.

Guest Editorial: Introduction to the Special Issue on Optical Detectors

The objective of this special issue is to document the current state-of-the-art in the area of Optical Detectors and highlight recent progress and trends in innovative optical detector technology and its applications. This issue combines 11 invited and 21 contributed papers, authored byworld-renowned research groups and promising scientists from around the world. The invited papers present extended reviews on recent progress and significant perspectives on future research directions. They cover lownoise linear-mode avalanche photodiodes (APDs) for fiber optic communications, single photon APDs (SPADs) and Si SPAD arrays for photon counting imagers, hybrid integration technologies, waveguide APDs, lowcapacitance nano-photodetector, integrated photodetectors for coherent receivers, and high-speed uni-traveling carrier (UTC) photodiodes (PDs) for THz applications. The contributed papers cover a broad variety of key research areas and emerging technologies in optical detectors including graphene-based detectors, plasmonic structures for current enhancement, phototransistors, and UTC-type PDs on silicon-on-insulator waveguide as well as a UTC PD with type II hybrid absorber. Several papers describe advances in SPADs and CMOS SPAD arrays for UV and visible detection and four papers cover quantum well and quantum dot devices. This special issue also illustrates a wide range of optical detector technology applications including UV, visible, and IR imaging, fiber optic communications, microwave and THz analog applications, and quantum communications. Furthermore, this special issue covers a range of advances on theory and simulation, design and fabrication, and optical detector characterization methodologies.

Total-Ionizing-Dose Effects on a Graphene X-Ray Detector Laser-Scribed From Graphene Oxide

We have evaluated the total-ionizing-dose response of graphene-based X-ray detectors fabricated from graphene oxide (GO) via laser scribing. Raman characterization shows that the resulting structures exhibit the desired conversion of GO to graphene; both high- and low-resistance detectors are formed. The detectors are quite radiation sensitive, as demonstrated by fast pulse testing. The response time of the detectors degrades with total-ionizing dose exposure as a result of electron trapping at residual oxygen from unreacted GO and/or adsorbed oxygen on the graphene surface.

Broadband graphene-based photoacoustic microscopy with high sensitivity.

Photoacoustic microscopy (PAM) enables the measurement of properties associated with optical absorption within tissues and complements sophisticated technologies employing optical microscopy. An inadequate frequency response as determined by a piezoelectric ultrasonic transducer results, however, in poor depth resolution and inaccurate measurements of the coefficients of optical absorption. We developed a PAM system configured as an attenuated total reflectance sensor with a ten-layer graphene film sandwiched between a prism and water (the coupling medium) for photoacoustic (PA) wave detection. Transients of the PA pressure cause perturbations in the refractive index of the water thereby changing the polarization-dependent absorption of the graphene film. The signal in PA detection involves recording the difference in the temporal-varying reflectance intensity between the two orthogonally polarized probe beams. The graphene-based sensor has an estimated noise-equivalent-pressure sensitivity of ∼550 Pa over an approximately linear pressure response from 11.0 kPa to 55.0 kPa. Moreover, it enables a much broader PA bandwidth detection of up to ∼150 MHz, primarily dominated by a highly localized evanescent field. From the strong optical absorption of inherent hemoglobin, in vivo label-free PAM imaging provided a three-dimensional viewing of the microvasculature of a mouse ear. These results suggest great potential for graphene-based PAM in biomedical investigations, such as microcirculation studies.

Designing graphene absorption in a multispectral plasmon-enhanced infrared detector.

We have examined graphene absorption in a range of graphene-based infrared devices that combine either monolayer or bilayer graphene with three different gate dielectrics. Electromagnetic simulations show that the optical absorption in graphene in these devices, an important factor in a functional graphene-based detector, is strongly dielectric-dependent. These simulations reveal that plasmonic excitation in graphene can significantly influence the percentage of light absorbed in the entire device, as well as the graphene layer itself, with graphene absorption exceeding 25% in regions where plasmonic excitation occurs. Notably, the dielectric environment of graphene has a dramatic influence on the strength and wavelength range over which the plasmons can be excited, making dielectric choice paramount to final detector tunability and sensitivity.

Studying thermal performance of the PIN-photodiode photodetectors based on MGL and GNR

The novel approach proposed in the present study is to use graphene based materials in the structure of the available infrared photo detectors in order to improve their parameters. The photo detector under study is PIN photodiode photodetector with no internal gain, but a very wide wavelength. In this paper, we have shown that the graphene-based detectors can exhibit high responsivity and detectivity at elevated temperatures in a wide radiation spectrum due to high values of the quantum efficiency and relatively low rates of thermo generation which lead them to surpass other detectors substantially.

Graphene-based mid-infrared room-temperature pyroelectric bolometers with ultrahigh temperature coefficient of resistance

There is a growing number of applications demanding highly sensitive photodetectors in the mid-infrared. Thermal photodetectors, such as bolometers, have emerged as the technology of choice, because they do not need cooling. The performance of a bolometer is linked to its temperature coefficient of resistance (TCR, ∼2–4% K−1 for state-of-the-art materials). Graphene is ideally suited for optoelectronic applications, with a variety of reported photodetectors ranging from visible to THz frequencies. For the mid-infrared, graphene-based detectors with TCRs ∼4–11% K−1 have been demonstrated. Here we present an uncooled, mid-infrared photodetector, where the pyroelectric response of a LiNbO3 crystal is transduced with high gain (up to 200) into resistivity modulation for graphene. This is achieved by fabricating a floating metallic structure that concentrates the pyroelectric charge on the top-gate capacitor of the graphene channel, leading to TCRs up to 900% K−1, and the ability to resolve temperature variations down to 15 μK.

Graphene-Based FET Detector forE. coliK12 Real-Time Monitoring and Its Theoretical Analysis

This paper presents a theoretical analysis for a graphene-based FET real-time detector of the target bacteriaE. coliK12. The motivation for this study is to design a sensor device for detection of bacteria in food and water in order to guarantee food safety. Graphene is chosen as our material for sensor design, which has outstanding electrical, physical, and optical performance. In our sensor structure, graphene-based solution gate field effect transistor (FET) is the device model; fabrication and functionalization protocol are presented together in this paper. What is more, a real-time signal display system is the accompanied equipment for our designed biosensor device. In this system, the sensor bias current signalIdswould change obviously when the target bacteria are attached to the sensor surface. And the bias currentIdsincreases when theE. coliconcentration increases. In the latter part, a theoretical interpretation of the sensor signal is to explain the bias currentIdsincreasing after theE. coliK12 attachment.

Fabrication of high sensitive and fast response MIR photodetector based on a new hybrid graphene structure

Electronic structure and morphology variation in a novel synthesized surface modified graphene from both experimental results and calculations based on ab-initio density functional theory results has been presented in this paper. The results indicate that modification of surface of graphene using organic molecule (thiosemicarbazide) causes sheet strain which results morphology and band structure variations. Therefore, tuning of the graphene band gap could be achieved by surface modification using organic molecule which is required in electronic device applications. Here, modified graphene is used as Mid IR detector and the results are compared with unmodified graphene-based detector. Improved detection parameters such as fast response time (three orders of magnitude faster than those reported in the literature), high sensitivity, low dark current and electrical stability are achievable for modified graphene-based fabricated detectors. These improvements are obtained because of introducing electron trapping centres and creating a bandgap in graphene through band structure engineering.