Low Noise Equivalent Power Research Articles

Plasmonic Nanoneedle Arrays with Enhanced Hot Electron Photodetection for Near‐IR Imaging

AbstractHot electron photodetection based on metallic nanostructures is attracting significant attention due to its potential to overcome the limitation of the traditional semiconductor bandgap. To enable efficient hot electron photodetection for practical applications, it is necessary to achieve broadband and perfect light absorption within extremely thin plasmonic nanostructures using cost‐effective fabrication techniques. In this study, an ultrahigh optical absorption (up to 97.3% in average across the spectral range of 1200−2400 nm) is demonstrated in the ultrathin plasmonic nanoneedle arrays (NNs) with thickness of 10 nm, based on an all‐wet metal‐assisted chemical etching process. The efficient hot electron generation, transport, and injection at the nanoscale apex of the nanoneedles facilitate the photodetector to achieve a record low noise equivalent power (NEP) of 4.4 × 10−12 W Hz−0.5 at the wavelength of 1300 nm. The hot‐electron generation and injection process are elucidated through a transport model based on a Monte Carlo approach, which quantitatively matches the experimental data. The photodetector is further integrated into a light imaging system, as a demonstration of the exceptional imaging capabilities at the near‐IR regime. The study presents a lithography‐free, scalable, and cost‐effective approach to enhance hot electron photodetection, with promising prospects for future imaging systems.

Highly responsive self-driven broadband photodetector based on MoS2 nanorods/β-Ga2O3 heterojunction

Gallium oxide (Ga2O3) has drawn significant interest in developing high-performance deep-ultraviolet photodetector, but detection of broadband range from ultraviolet C to near-infrared remains a substantial challenge. The construction of heterojunction effectively broadens the spectral range for fabricating broadband photodetection devices with exciting optical and electrical properties. This work introduces a heterojunction comprised of horizontally aligned MoS2 nanorods on β-Ga2O3 nanogranules. The high-performing developed MoS2/β-Ga2O3 device operates in a self-driven mode in the broad spectral range from ultraviolet C -visible-near infrared (UVC-VIS-NIR). The device exhibits an ultralow dark current of 79 nA and a maximum responsivity of 94.92, 7.97, and 44.04 mAW−1 for UV (266 nm), Vis (625 nm), and NIR (950 nm) light illumination in self-driven conditions. Furthermore, the fabricated device shows the highest responsivity of 4.2 × 104 mAW−1, with a high external quantum efficiency of 1.97 × 104% and extremely low noise equivalent power of 4.03 × 10−14 WHz−1/2, under 266 nm light illumination at an applied bias of 5V. This study paves the way to develop MoS2/β-Ga2O3 based broadband photodetector for constructing high-performance self-driven optoelectronics devices with low power consumption.

Self-driven Vis-NIR broadband photodetector based on nano-hedge-like MoS2/WSe2 heterostructure

TMDC heterostructures provide alternative bases for optoelectronic devices besides conventional Schottky devices. With the continued expansion of the modern semiconductor industry, self-powered devices have emerged as an integral part of electronic and optoelectronic equipments. This work reports a unique seamless nano-hedge (nh) like morphology of MoS2 deposited on WSe2 film to form nh-MoS2/WSe2 heterostructure as a self-powered photodetector with a broad spectral range from visible to NIR. The developed heterostructure exhibits a very high responsivity of 900 mAW-1 when illuminated by 860 nm under zero bias (self-powered mode). In addition, the device also shows a high responsivity of 177 mAW-1, 271 mAW-1, and 506 mAW-1 for illumination of 532 nm, 625 nm light, and 950 nm, respectively, at zero applied bias. With low noise equivalent power of 2.6 × 10-14 WHz1/2 and ultra-high responsivity of 2.6 × 104 mAW-1 in photoconductive mode at 860 nm light irradiation, the device exhibits extremely high external quantum efficiency of 6.29 × 103%. Further, the device also displays detectivity of 5 × 1011 Jones, an LDR value of 26 dB, with a fast response time of 15 ms. Developing a broadband photodetector based on nh-MoS2/WSe2 heterostructure opens the route for highly responsive, self-powered future optoelectronic devices.

Millimeter-wave to near-terahertz sensors based on reversible insulator-to-metal transition in VO2

In the quest for low power bio-inspired spiking sensors, functional oxides like vanadium dioxide are expected to enable future energy efficient sensing. Here, we report uncooled millimeter-wave spiking detectors based on the sensitivity of insulator-to-metal transition threshold voltage to the incident wave. The detection concept is demonstrated through actuation of biased VO2 switches encapsulated in a pair of coupled antennas by interrupting coplanar waveguides for broadband measurements, on silicon substrates. Ultimately, we propose an electromagnetic-wave-sensitive voltage-controlled spike generator based on VO2 switches in an astable spiking circuit. The fabricated sensors show responsivities of around 66.3 MHz.W−1 at 1 μW, with a low noise equivalent power of 5 nW.Hz−0.5 at room temperature, for a footprint of 2.5 × 10−5 mm2. The responsivity in static characterizations is 76 kV.W−1. Based on experimental statistical data measured on robust fabricated devices, we discuss stochastic behavior and noise limits of VO2 -based spiking sensors applicable for wave power sensing in mm-wave and sub-terahertz range.

Highly Sensitive Long‐Wave Infrared Photodetector Based on Two‐Dimensional Hematite α‐Fe2O3

AbstractAmbient temperature long‐wavelength infrared (LWIR) photodetection has many critical applications ranging from thermal imaging and optical communications to night vision cameras. Currently, high performance, low cost, air stability, and ultra‐broadband response still constitute challenges. Here, the study demonstrates a high‐performance uncooled LWIR photodetector using 2D hexagonal α‐Fe2O3 single crystal nanoflakes, which are synthesized via chemical vapor deposition. The 2D α‐Fe2O3 photodetector realizes high specific detectivity (D*) of 3.28×109 cmHz1/2 W−1 and very low noise equivalent power of 8.94×10−14 W Hz−1/2 with 10.6 µm laser. The photo bolometer effect is responsible for the photoresponse in the infrared range with a large temperature coefficient resistance of −241.2% K−1. This study shows a new type of potential broadband response material and provides a promising LWIR optoelectrical device with good air stability.

Self‐Driven Fast‐Speed Photodetector Based on BP/ReS2 van der Waals Heterodiode

AbstractBroadband photodetectors based on 2D layered materials provide great potential applications in night vision, sensing, and communications. However, it remains a challenge for detectors to achieve both high photoresponsivity and fast response. Here, a high‐sensitive photodetector based on ReS2/BP van der Waals (vdW) heterodiode with fast speed, rising time (τr) of 770 ns, and decay time (τd) of 760 ns under a 637 nm laser is reported. The detection range is covered from visible to mid‐wave infrared (MWIR) 0.405–3.753 μm. In the visible range, a high photoresponsivity of 107.1 AW−1, competitive specific detectivity (D*) of 1.89 × 1010 cm Hz1/2 W−1, and a low noise equivalent power of 3.03 × 10−14 W Hz−1/2 are obtained. In the MWIR the D* of 3.26 × 108 cm Hz1/2 W−1 is demonstrated in the photovoltaic model. Notably, the photodiode realizes a high external quantum efficiency of 71.8%, and a high power conversion efficiency of 2.0%. This work provides a way to design broadband response and fast‐speed self‐driven photodetectors with great potential applications in weak light intensity.

Fast Switching of Bolometric and Self‐Powered Effects in 2H‐NbSe2 for High‐Efficiency Low‐Energy Photon Harvesting

AbstractThe high‐performance detector that operates at the low‐photon‐energy range (≈meV) of the electromagnetic spectrum at room temperature remains in urgent demand for application in a variety of important sectors, including 6G communications, security, sensing, medicine, space science, etc. The vast range of 2D‐layered nanomaterials and their distinct layer structures provide an ideal foundation for the manufacture of sophisticated photodetectors and detectors with convenient fabrication methods. In this paper, the direct detection of terahertz waveband dominated by the bolometer effect and photo‐thermoelectric effect is demonstrated, which is endowed with a versatile integration of 2H‐NbSe2 in terms of planar and vertical van der Waals structures. This 2H‐NbSe2‐based device can detect broadband long wavelength due to the bolometer effect, and the van der Waals heterostructure‐based device exhibits excellent sensitivity and self‐powered photo‐thermoelectric conversion with high responsivity (>735 V W−1), low response time (<1 µs), as well as low noise equivalent power (NEP < 50 pW Hz−0.5) at room temperature. The photodetector engineers versatile detection mechanisms, displaying low‐energy photons on the hybrid integration of novel low‐dimensional materials and providing an opportunity for the practical application of energy harvesting.

High-performance metal electrode-enhanced double parallel p–n heterojunctions photodetector

Highly sensitive uncooled mid-wave infrared (MWIR) photodetectors have a very wide range of applications ranging from the sensor and image to communications. Traditional MWIR detection semiconductors require liquid nitrogen cooling to depress dark current, which impeded the wide applications of devices. Here, we report a metal electrode-enhanced double parallel BP/InSe/BP van der Waals heterostructure uncooled MWIR photodetector. The device exhibits ultrahigh light on/off ratio of 108 and a very low dark current of 0.16 pA. The competitive performance includes high photoresponsivity (R) of 27.8 A W−1, excellent specific detectivity (D*) of 3.8 × 1012 cm Hz1/2 W−1, very low noise equivalent power (NEP) of 3.7 × 10−16 W Hz−1/2, and fast response speed of τr = 3.5 μs and τd = 2.4 μs in the visible range. Notably, in the MWIR range, the light on/off ratio of ∼104, NEP of 3.0 × 10−13 W Hz−1/2, and D* of 4.8 × 109 cm Hz1/2 W−1 was realized. The work sheds light on developing a high-performance uncooled MWIR photodetector by designed band alignment.

Ultrahigh-Sensitivity and Fast-Speed Solar-Blind Ultraviolet Photodetector Based on a Broken-Gap van der Waals Heterodiode.

Broad-bandgap semiconductor-based solar-blind ultraviolet (SBUV) photodetectors have attracted considerable research interest because of their broad applications in missile plume tracking, flame detectors, environmental monitoring, and optical communications due to their solar-blind nature and high sensitivity with low background radiation. Owing to its high light absorption coefficient, abundance, and wide tunable bandgap of 2-2.6 eV, tin disulfide (SnS2) has emerged as one of the most promising compounds for application in UV-visible optoelectronic devices. However, SnS2 UV detectors have some undesirable properties such as slow response speed, high current noise level, and low specific detectivity. This study reports a metal mirror-enhanced Ta0.01W0.99Se2/SnS2 (TWS) van der Waals heterodiode-based SBUV photodetector with an ultrahigh photoresponsivity (R) of ∼1.85 × 104 AW-1 and a fast speed with rising time (τr) of 3.3 μs and decay time (τd) of 3.4 μs. Notably, the TWS heterodiode device exhibits a significantly low noise equivalent power of ∼1.02 × 10-18 W Hz-1/2 and a high specific detectivity of ∼3.65 × 1014 cm Hz1/2 W-1. This study provides an alternative method for designing fast-speed SBUV photodetectors with enormous potential in applications.

Self-Powered Photodetector Based on a Ag Nanoparticle-Decorated Gd2O3 Nanorod

A self-powered photodetector based on a silver nanoparticle (Ag NP)-decorated gadolinium oxide nanorod (Gd2O3 NR) has been deposited using the glancing angle deposition (GLAD) technique. Field emission gun scanning electron microscopy (FEG-SEM) and transmission electron microscopy (TEM) analyses confirm the successful growth of a Ag NP-decorated Gd2O3 NR with polycrystalline nature. UV–vis spectroscopy reveals the presence of the Ag NP and Gd2O3 NR with photon absorption in visible and UV regions. The electrical analysis was studied for the voltage range of −5 to 5 V. The device demonstrated self-powered characteristics with a significantly low dark current of 0.73 nA. In addition, the device also displayed a stable switching response with a rise/fall time of 0.18/0.17 s at 0 V. Moreover, the device obtained good responsivity (11.8 mA/W) with a high detectivity of 7.63 × 1011 Jones and a low noise equivalent power of 3.67 × 10–12 W at 0 V.

Plasma-treated carbon nanotubes for fast infrared bolometers

Carbon nanotube films are a promising class of materials for bolometric photodetectors due to a unique combination of extremely thin (nm-sized) free-standing form factor with small thermal capacity and intriguing electronic and optical properties, thereby, ensuring high sensitivity and high speed of operation. Nevertheless, the key parameter for bolometric sensor material—the temperature coefficient of resistance (TCR)—is unacceptably low limiting the application of the carbon nanotube films. Here, we examine the plasma treatment of single-walled carbon nanotube (SWCNT) films as the effective method for the TCR enhancement. We study the effect of different plasma gases (oxygen, nitrogen, and hydrogen) on the conductivity of treated films. Also, we investigate the effect of defectiveness, length, and bundling degree of the SWCNTs on TCR. The optimized procedure allows to increase the TCR up to 1.7% K−1 by modulus at 100 K and to 0.8% K−1 at 300 K. The bolometer prototypes based on the plasma-treated SWCNT films demonstrate high sensitivity over a wide IR range (∼21 V/W), a short response time (∼1 ms), and low noise equivalent power (∼8 × 10−9 W Hz−1/2) at the temperature of 100 K.

Acid-modified CNT/Zinc Oxide nanowires based high performance broadband photodetector

In this study, the authors have reported the impact of post-treatment via exposure to acid on single walled carbon nanotubes (SWNTs) thin film (TF) based SWNT/ZnO Nanowire (NW) broad band photodetector. The ZnO NWs were deposited on SWNT (with and without acid-treated) using a simple catalytic free process called glancing angle deposition (GLAD) technique. Acid-treated SWNT samples warranted the growth of high quality ZnO NWs over them. On fabricating photodetectors with the acid-treated ZnO NW/SWNT TF heterostructure (HS) gave better device performance as compared to the as-deposited ZnO NW/SWNT TF HS (without acid-treatment) sample. The acid-treated device showed a large responsivity (85.45 A/W), specific detectivity (0.859 × 1012 Jones) and with a low noise equivalent power of 3.9101 pW values. Moreover, the oxygen adsorption–desorption mechanism in SWNTs impacted the electrical resistance of the nanotubes which affected nanotube conductivity. The acid-treatment favoured relatively faster charge separation at the ZnO NW/SWNT heterojunction thus providing a fast device response (trise = 0.11 s, tfall = 0.39 s at + 5 V). The fabricated acid-treated device showed good broad band detection (250 nm-750 nm) which was explained with respect to the optical absorption profile of the sample.

High-performance infrared photodetection beyond bandgap limitation based on surface plasmon resonance in sub-stoichiometry molybdenum oxide nanostructures

High-performance photodetectors in the near-infrared (NIR) regime are essential for many advanced applications, such as optical communication, intelligent driving, and imaging system. However, conventional photoconductive infrared detectors commonly suffer from slow response speed and narrow spectral response. Here, we demonstrate a high performance NIR photodetector based on plasmonic sub-stoichiometry molybdenum oxide (MoO3−x) nanostructures/graphene heterostructure. Empowered by surface plasmon resonance induced near-field enhancement in MoO3−x and the subsequent hot-electron injection (HEI), a fast response time (rise time ∼6.7 μs, decay time ∼12.5 μs), high responsivity (3.3 A/W), low noise equivalent power (∼4.9 pW/Hz1/2), as well as wide response range from visible light to NIR is obtained at room temperature. The weak carrier–phonon interaction in graphene prevents the relaxation of injected hot electrons and enables efficient electron extraction. The response speed is nearly four orders of magnitude improved compared with other graphene-based hybrid devices with similar device structures. Moreover, the interfacial HEI breaks the bandgap limits of molybdenum oxide and further extends the response spectrum of the device to conventional band (C-band) of optical communication. Our proposed device architecture offers new strategy for developing high-performance infrared photodetectors.

Boosting the Sensitivity of WSe2 Phototransistor via Janus Interfaces with 2D Perovskite and Ferroelectric Layers

Hybrid systems have recently attracted increasing attention, which combine the special attributes of each constitute and create interesting functionalities through multiple heterointerface interactions. Here, we design a two-dimensional (2D) hybrid phototransistor utilizing Janus-interface engineering, in which the WSe2 channel combines light-sensitive perovskite and spontaneously polarized ferroelectrics, achieving collective ultrasensitive detection performance. The top perovskite (BA2(MA)3Pb4I13) layer can absorb the light efficiently and provide generous photoexcited holes to WSe2. WSe2 exhibit p-type semiconducting states of different degrees due to the selective light-operated doping effect, which also enables the ultrahigh photocurrent of the device. The bottom ferroelectric (Hf0.5Zr0.5O2) layer dramatically decreases the dark current, which should be attributed to the ferroelectric polarization assisted charge trapping effect and improved gate control. As a whole, our phototransistors show excellent photoelectric performances across the ultraviolet to near-infrared range (360-1050 nm), including an ultrahigh ON/OFF current ratio > 109 and low noise-equivalent power of 1.3 fW/Hz1/2, all of which are highly competitive in 2D semiconductor-based optoelectronic devices. In particular, the devices show excellent weak light detection ability, where the distinguishable photoswitching signal is obtained even under a record-low light intensity down to 1.6 nW/cm2, while showing a high responsivity of 2.3 × 105 A/W and a specific detectivity of 4.1 × 1014 Jones. Our work demonstrates that Janus-interface design makes the upper and lower interfaces complement each other for the joint advancement into high-performance optoelectronic applications, providing a picture to realize the integrated engineering on carrier dynamics by light irradiation, electric field, interfacial trapping, and band alignment.

Interdigitated electrodes connected WO3 nanowire arrays for high performance UV photodetection

In this article, MSM based Au/WO3 Nanowires (NWs) were fabricated on n-type silicon substrate using glancing angle deposition inside the RF sputtering chamber for high performance ultraviolet photodetector (UV-PD). The field emission scanning electron microscope analysis shows uniform and vertically oriented WO3 NWs on Si substrate. The non-linear I-V characteristics of the device represents that there is good Schottky junction formation at the metal–semiconductor interface. The fabricated Au/WO3 NW/Si device showed high responsivity of 462.6 A/W, specific detectivity of 1.06 × 1013 Jones and a low noise-equivalent power of 3.17 × 10−13 respectively, under 380 nm light illumination. A fast UV-PD response of 2.7 ms and 2.8 ms was obtained at 0 V.

High Performance of Zero-Power-Consumption MOCVD-Grown β-Ga2O3-Based Solar-Blind Photodetectors with Ultralow Dark Current and High-Temperature Functionalities.

In this article, we report on high-performance deep ultraviolet photodetectors (DUV PDs) fabricated on metal-organic chemical vapor deposition (MOCVD)-grown β-Ga2O3 heteroepitaxy that exhibit stable operation up to 125 °C. The fabricated DUV PDs exhibit self-powered behavior with an ultralow dark current of 1.75 fA and a very high photo-to-dark-current ratio (PDCR) of the order of 105 at zero bias and >105 at higher biases of 5 and 10 V, which remains almost constant up to 125 °C. The high responsivity of 6.62 A/W is obtained at 10 V at room temperature (RT) under the weak illumination of 42.86 μW/cm2 of 260 nm wavelength. The detector shows very low noise equivalent power (NEP) of 5.74 × 10-14 and 1.03 × 10-16 W/Hz1/2 and ultrahigh detectivity of 5.51 × 1011 and 3.10 × 1014 Jones at 0 and 5 V, respectively, which shows its high detection sensitivity. The RT UV-visible (260:500 nm) rejection ratios of the order of 103 at zero bias and 105 at 5 V are obtained. These results demonstrate the potential of Ga2O3-based DUV PDs for solar-blind detection applications that require high-temperature robustness.

MoS2-on-GaN Plasmonic Photodetector Using a Bowtie Striped Antenna Structure

The layered semiconductor material molybdenum disulfide (MoS2) has led to an upsurge in research for applications in optoelectric devices that benefit from its excellent optical and electrical properties. The application of the plasmonic structure to enhance light–matter interaction and intensity of the light field via localized surface plasmon resonance provides a promising method for MoS2-based devices for improving performance. In this work, we have prepared a plasmon-enhanced few-layer MoS2 photodetector based on a gallium nitride substrate using a bowtie equal grid antenna structure, and the large-scale few-layer MoS2 growth on the GaN substrate is realized by chemical vapor deposition. The enhancement MoS2 plasmonic photodetector achieves a high responsivity R of 0.82 A/W, a low noise equivalent power NEP of 6.58 × 10–14 W/Hz1/2, and a detectivity of 1.56 × 1012 Jones under 365 nm at 5 V bias and a corresponding rise/fall time of 18/10 ms. With the enhanced performance of the photodetector demonstrated, the as-fabricated plasmonic structure proposed a feasibility method to achieve enhanced photoresponse and is applicable to other high-efficiency photoelectric devices.

Improving performance of ZnO Schottky photodetector by inserting MXenes modified-layer

The development of low-cost and high-performance ZnO Schottky photodetectors (PDs) has drawn intensive attention, but still a challenge due to their poor conductivity and low light utilization efficiency. Here, we introduce Ti3C2TX into ZnO films to fabricate Schottky UV PDs via facile spin-coated method. The fabricated ZnO/Ti3C2TX/ZnO compound film shows outstanding performance on photocurrent, responsivity, noise equivalent power (NEP), normalized detection rate (D*), and linear dynamic region (LDR), compared with the original ZnO device. The photocurrent is significantly increased by 466%, and the responsivity is improved by one order of magnitude. In addition, it exhibits relatively low NEP (5.99 × 10−11 W), strong D* (2.53 × 109 Jones), and high LDR (28 dB). The superior performance is ascribed to the enhanced conductivity and light absorption of ZnO film after introduction of Ti3C2TX modification layer, leading to simultaneously faster electron transfer, lower the radiation recombination of electron and holes on the ZnO/Ti3C2TX/ZnO compound film. This work provides a facile way to develop low-cost and high-performance ZnO Schottky PDs.

High photon detection efficiency InGaAs/InP single photon avalanche diode at 250 K

Planar semiconductor InGaAs/InP single photon avalanche diodes with high responsivity and low dark count rate are preferred single photon detectors in near-infrared communication. However, even with well-designed structures and well-controlled operational conditions, the performance of InGaAs/InP SPADs is limited by the inherent characteristics of avalanche process and the growth quality of InGaAs/InP materials. It is difficult to ensure high detection efficiency while the dark count rate is controlled within a certain range at present. In this paper, we fabricated a device with a thick InGaAs absorption region and an anti-reflection layer. The quantum efficiency of this device reaches 83.2%. We characterized the single-photon performance of the device by a quenching circuit consisting of parallel-balanced InGaAs/InP single photon detectors and single-period sinusoidal pulse gating. The spike pulse caused by the capacitance effect of the device is eliminated by using the characteristics of parallel balanced common mode signal elimination, and the detection of small avalanche pulse amplitude signal is realized. The maximum detection efficiency is 55.4% with a dark count rate of 43.8 kHz and a noise equivalent power of 6.96 × 10−17 W/Hz1/2 at 247 K. Compared with other reported detectors, this SPAD exhibits higher SPDE and lower noise-equivalent power at a higher cooling temperature.

Fully Depleted Self-Aligned Heterosandwiched Van Der Waals Photodetectors.

Room-temperature-operating highly sensitive mid-wavelengthinfrared (MWIR) photodetectors are utilized in a large number of important applications, including night vision, communications, and optical radar. Many previous studies have demonstrated uncooled MWIR photodetectors using 2D narrow-bandgap semiconductors. To date, most of these works have utilized atomically thin flakes, simple van der Waals (vdW) heterostructures, or atomically thin p-n junctions as absorbers, which have difficulty in meeting the requirements for state-of-the-art MWIR photodetectors with a blackbody response. Here, a fully depleted self-aligned MoS2 -BP-MoS2 vdW heterostructure sandwiched between two electrodes is reported. This new type of photodetector exhibits competitive performance, including a high blackbody peak photoresponsivity up to 0.77AW-1 and low noise-equivalent power of 2.0×10-14 WHz-1/2 , in the MWIR region. A peak specific detectivity of 8.61×1010 cm Hz1/2 W-1 under blackbody radiation is achieved at room temperature in the MWIR region. Importantly, the effective detection range of the device is twice that of state-of-the-art MWIR photodetectors. Furthermore, the device presents an ultrafast response of ≈4µs both in the visible and short-wavelength infrared bands. These results provide an ideal platform for realizing broadband and highly sensitive room-temperature MWIR photodetectors.