Showing papers on "Photodiode published in 2021"

Self-Powered MXene/GaN van der Waals Heterojunction Ultraviolet Photodiodes with Superhigh Efficiency and Stable Current Outputs

Abstract: A self-powered, high-performance Ti3 C2 Tx MXene/GaN van der Waals heterojunction (vdWH)-based ultraviolet (UV) photodiode is reported. Such integration creates a Schottky junction depth that is larger than the UV absorption depth to sufficiently separate the photoinduced electron/hole pairs, boosting the peak internal quantum efficiency over the unity and the external quantum efficiency over 99% under weak UV light without bias. The proposed Ti3 C2 Tx /GaN vdWH UV photodiode demonstrates pronounced photoelectric performances working in self-powered mode, including a large responsivity (284 mA W-1 ), a high specific detectivity (7.06 × 1013 Jones), and fast response speed (rise/decay time of 7.55 µs/1.67 ms). Furthermore, the remarkable photovoltaic behavior leads to an impressive power conversion efficiency of 7.33% under 355 nm UV light illumination. Additionally, this work presents an easy-processing spray-deposition route for the fabrication of large-area UV photodiode arrays that exhibit highly uniform cell-to-cell performance. The MXene/GaN photodiode arrays with high-efficiency and self-powered ability show high potential for many applications, such as energy-saving communication, imaging, and sensing networks.

Ultra-fast germanium photodiode with 3-dB bandwidth of 265 GHz

Abstract: On a scalable silicon technology platform, we demonstrate photodetectors matching or even surpassing state-of-the-art III–V devices. As key components in high-speed optoelectronics, photodetectors with bandwidths greater than 100 GHz have been a topic of intense research for several decades. Solely InP-based detectors could satisfy the highest performance specifications. Devices based on other materials, such as germanium-on-silicon devices, used to lag behind in speed, but enabled complex photonic integrated circuits and co-integration with silicon electronics. Here we demonstrate waveguide-coupled germanium photodiodes with optoelectrical 3-dB bandwidths of 265 GHz and 240 GHz at a photocurrent of 1 mA. This outstanding performance is achieved by a novel device concept in which a germanium fin is sandwiched between complementary in situ-doped silicon layers. Our photodetectors show internal responsivities of 0.3 A W−1 (265 GHz) and 0.45 A W−1 (240 GHz) at a wavelength of 1,550 nm. The internal bandwidth–efficiency product of the latter device is 86 GHz. Low dark currents of 100–200 nA are obtained from these ultra-fast photodetectors. By sandwiching a germanium fin between complementary in situ-doped silicon layers, a waveguide-coupled germanium photodiode with a 3-dB bandwidth of 265 GHz, accompanied by high responsivity and low dark current, is realized.

Highly sensitive active pixel image sensor array driven by large-area bilayer MoS2 transistor circuitry

Abstract: Various large-area growth methods for two-dimensional transition metal dichalcogenides have been developed recently for future electronic and photonic applications. However, they have not yet been employed for synthesizing active pixel image sensors. Here, we report on an active pixel image sensor array with a bilayer MoS2 film prepared via a two-step large-area growth method. The active pixel of image sensor is composed of 2D MoS2 switching transistors and 2D MoS2 phototransistors. The maximum photoresponsivity (Rph) of the bilayer MoS2 phototransistors in an 8 × 8 active pixel image sensor array is statistically measured as high as 119.16 A W−1. With the aid of computational modeling, we find that the main mechanism for the high Rph of the bilayer MoS2 phototransistor is a photo-gating effect by the holes trapped at subgap states. The image-sensing characteristics of the bilayer MoS2 active pixel image sensor array are successfully investigated using light stencil projection. Here, the authors report the realization of an active pixel image sensor array composed by 64 pairs of switching transistors and phototransistors, based on wafer-scale bilayer MoS2. The device exhibits sensitive photoresponse under RGB light illumination, showing the potential of 2D MoS2 for image sensing applications.

An Ultrafast WSe2 Photodiode Based on a Lateral p-i-n Homojunction.

Abstract: High-quality homogeneous junctions are of great significance for developing transition metal dichalcogenides (TMDs) based electronic and optoelectronic devices. Here, we demonstrate a lateral p-type/intrinsic/n-type (p-i-n) homojunction based multilayer WSe2 diode. The photodiode is formed through selective doping, more specifically by utilizing self-aligning surface plasma treatment at the contact regions, while keeping the WSe2 channel intrinsic. Electrical measurements of such a diode reveal an ideal rectifying behavior with a current on/off ratio as high as 1.2 × 106 and an ideality factor of 1.14. While operating in the photovoltaic mode, the diode presents an excellent photodetecting performance under 450 nm light illumination, including an open-circuit voltage of 340 mV, a responsivity of 0.1 A W-1, and a specific detectivity of 2.2 × 1013 Jones. Furthermore, benefiting from the lateral p-i-n configuration, the slow photoresponse dynamics including the photocarrier diffusion in undepleted regions and photocarrier trapping/detrapping due to dopants or doping process induced defect states are significantly suppressed. Consequently, a record-breaking response time of 264 ns and a 3 dB bandwidth of 1.9 MHz are realized, compared with the previously reported TMDs based photodetectors. The above-mentioned desirable properties, together with CMOS compatible processes, make this WSe2p-i-n junction diode promising for future applications in self-powered high-frequency weak signal photodetection.

Enhanced responsivity and detectivity of fast WSe2 phototransistor using electrostatically tunable in-plane lateral p-n homojunction.

Abstract: Layered transition metal dichalcogenides have shown tremendous potential for photodetection due to their non-zero direct bandgaps, high light absorption coefficients and carrier mobilities, and ability to form atomically sharp and defect-free heterointerfaces. A critical and fundamental bottleneck in the realization of high performance detectors is their trap-dependent photoresponse that trades off responsivity with speed. This work demonstrates a facile method of attenuating this trade-off by nearly 2x through integration of a lateral, in-plane, electrostatically tunable p-n homojunction with a conventional WSe2 phototransistor. The tunable p-n junction allows modulation of the photocarrier population and width of the conducting channel independently from the phototransistor. Increased illumination current with the lateral p-n junction helps achieve responsivity enhancement upto 2.4x at nearly the same switching speed (14–16 µs) over a wide range of laser power (300 pW–33 nW). The added benefit of reduced dark current enhances specific detectivity (D*) by nearly 25x to yield a maximum measured flicker noise-limited D* of 1.1×1012 Jones. High responsivity of 170 A/W at 300 pW laser power along with the ability to detect sub-1 pW laser switching are demonstrated. In photodetectors based on 2D materials, a trade-off often exists between responsivity and speed. Here, the authors attenuate this issue via integration of a lateral, in-plane, electrostatically tunable p-n homojunction with a conventional WSe2 phototransistor.

Fast Response Organic Tandem Photodetector for Visible and Near-Infrared Digital Optical Communications

Abstract: Organic photodetectors (OPDs), which usually work as photodiodes, photoconductors, or phototransistors, have emerged as candidates for next-generation light sensing. However, low response speed caused by low carrier mobility and resistance-capacitance (RC) time constant, severely hinders the commercialization of OPDs. Herein, the authors demonstrate a state-of-the-art OPD with a record response speed of 146.8 ns by employing tandem structure to simultaneously reduce both the carrier transit time and RC time constant of the device, which is faster than that of previously reported OPDs as far as they know. Moreover, benefitting from the multi-level barrier enhancement and voltage division engendered by tandem structure, an ultralow noise current of 7.82 × 10-14 A Hz-1/2 is obtained, as well as a wide detection range in 300-1000 nm. In addition, the tandem OPDs are successfully integrated into the optical communication system as signal receivers, demonstrating the precise digital signal communication from visible to near-infrared light. It is believed that tandem OPDs have promising application potential in the wireless transmission system.

A defect-induced broadband photodetector based on WS2/pyramid Si 2D/3D mixed-dimensional heterojunction with a light confinement effect.

Abstract: Broadband photodetection is of vital importance for both civil and technological applications. The widespread use of commercial photodiodes based on traditional semiconductors (e.g. GaN, Si, and InGaAs) is limited to the relatively narrow response range. In this work, we have demonstrated a self-driven and broadband photodetector based on WS2/pyramid Si 2D/3D mixed-dimensional van der Waals (vdW) heterojunction, which is assembled by directly transferring 2D WS2 film on 3D pyramid Si. Thanks to the enhanced light absorption with the pyramid Si structure, the defect-induced narrowed bandgap of the WS2 film, and high-quality vdW heterojunction, impressive device performances in terms of a large responsivity of 290 mA W−1, a high specific detectivity of up to 2.6 × 1014 Jones and an ultrabroad response spectrum ranging from 265 nm to 3.0 μm are achieved at zero bias. Importantly, the photodetector can function as an infrared imaging cell with a high spatial resolution. The totality of these excellent features confirms that the demonstrated WS2/pyramid Si 2D/3D mixed-dimensional vdW heterojunction device may hold great promise for applications in high-performance broadband infrared photodetection and imaging.

Mitigating Dark Current for High-Performance Near-Infrared Organic Photodiodes via Charge Blocking and Defect Passivation.

Abstract: Thin-film organic near-infrared (NIR) photodiodes can be essential building blocks in the rapidly emerging fields including the internet of things and wearable electronics. However, the demonstration of NIR organic photodiodes with not only high responsivity but also low dark current density that is comparable to that of inorganic photodiodes, for example, below 1 nA cm-2 for silicon photodiodes, remains a challenge. In this work, we have demonstrated non-fullerene acceptor-based NIR photodiodes with an ultralow dark current density of 0.2 nA cm-2 at -2 V by innovating on charge transport layers to mitigate the reverse charge injection and interfacial defect-induced current generation. The same device also shows a high external quantum efficiency approaching 70% at 850 nm and a specific detectivity of over 1013 Jones at wavelengths up to 940 nm. Furthermore, the versatility of our approach for mitigating dark current is demonstrated using a NIR photodetector utilizing different non-fullerene systems. Finally, the practical application of NIR organic photodiodes is demonstrated with an image sensor integrated on a silicon CMOS readout. This work provides new insight into the device stack design of low-dark current NIR organic photodiodes for weak light detection.

Near-Infrared Self-Powered Linearly Polarized Photodetection and Digital Incoherent Holography Using WSe2/ReSe2 van der Waals Heterostructure.

Abstract: Polarization-sensitive photodetection has attracted considerable attention as an emerging technology for future optoelectronic applications such as three-dimensional (3D) imaging, quantum optics, and encryption. However, traditional photodetectors based on Si or III-V InGaAs semiconductors cannot directly detect polarized light without additional optical components. Herein, we demonstrate a self-powered linear-polarization-sensitive near-infrared (NIR) photodetector using a two-dimensional WSe2/ReSe2 van der Waals heterostructure. The WSe2/ReSe2 heterojunction photodiode with semivertical geometry exhibits excellent performance: an ideality factor of 1.67, a broad spectral photoresponse of 405-980 nm with a significant photovoltaic effect, outstanding linearity with a linear dynamic range wider than 100 dB, and rapid photoswitching behavior with a cutoff frequency up to 100 kHz. Strongly polarized excitonic transitions around the band edge in ReSe2 lead to significant 980 nm NIR linear-polarization-dependent photocurrent. This linear polarization sensitivity remains stable even after exposure to air for longer than five months. Furthermore, by leveraging the NIR (980 nm)-selective linear polarization detection of this photodiode under photovoltaic operation, we demonstrate digital incoherent holographic 3D imaging.

Wide-Bandgap CaSnO3 Perovskite As an Efficient and Selective Deep-UV Absorber for Self-Powered and High-Performance p-i-n Photodetector.

Abstract: Calcium stannate (CaSnO3) is an inorganic perovskite material with an ultrawide bandgap (4.2-4.4 eV) that is associated with its unique structural characteristics. Owing to its remarkable optical and electric properties and high physical and chemical stability, it has recently drawn significant interest for various applications such as photocatalysts for the degradation of organic compounds and hydrogen production under UV radiation, gas sensors, and thermally stable capacitors. In this study, we demonstrate a self-powered deep-UV (DUV) p-i-n photodetector consisting of CaSnO3 thin film as an efficient DUV absorber via a low-temperature solution process. The physical, optical, and electrical properties of the as-synthesized CaSnO3 are characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, high-resolution transmission electron microscopy, ultraviolet-visible spectroscopy, photoluminescence spectroscopy, space charge limited current, and four-point probe measurements. As a key component in a p-i-n DUV photodetector, the thickness of the CaSnO3 absorber layer and operating bias are optimized to enhance charge carrier transport, light absorption, and signal-to-noise ratio. As a result, the optimized device shows a high performance at zero bias under 254 nm UV illumination: with a specific detectivity of 1.56 × 1010 Jones, fast rise/fall time of 80/70 ms, and high 254:365 nm photocurrent rejection ratio of 5.5 along with a stable photoresponse during 100 continuous cycles initially as well as after 1 month of storage. Accordingly, this study suggests that a novel CaSnO3-based photodiode prepared via a solution process can be employed for many practical DUV-detection applications.

An ultrasensitive molybdenum-based double-heterojunction phototransistor.

Abstract: Two-dimensional (2D) materials are promising for next-generation photo detection because of their exceptional properties such as a strong interaction with light, electronic and optical properties that depend on the number of layers, and the ability to form hybrid structures. However, the intrinsic detection ability of 2D material-based photodetectors is low due to their atomic thickness. Photogating is widely used to improve the responsivity of devices, which usually generates large noise current, resulting in limited detectivity. Here, we report a molybdenum-based phototransistor with MoS2 channel and α-MoO3-x contact electrodes. The device works in a photo-induced barrier-lowering (PIBL) mechanism and its double heterojunctions between the channel and the electrodes can provide positive feedback to each other. As a result, a detectivity of 9.8 × 1016 cm Hz1/2 W−1 has been achieved. The proposed double heterojunction PIBL mechanism adds to the techniques available for the fabrication of 2D material-based phototransistors with an ultrahigh photosensitivity. Here, the authors exploit a photo-induced barrier-lowering mechanism in MoS2/ α-MoO3-x heterojunctions to realize two-dimensional phototransistors with enhanced performance and fast response at low bias voltage.

Tunable Linearity of High-Performance Vertical Dual-Gate vdW Phototransistors

Abstract: Layered 2D semiconductors have been widely exploited in photodetectors due to their excellent electronic and optoelectronic properties. To improve their performance, photogating, photoconductive, photovoltaic, photothermoelectric, and other effects have been used in phototransistors and photodiodes made with 2D semiconductors or hybrid structures. However, it is difficult to achieve the desired high responsivity and linear photoresponse simultaneously in a monopolar conduction channel or a p-n junction. Here, dual-channel conduction with ambipolar multilayer WSe2 is presented by employing the device concept of dual-gate phototransistor, where p-type and n-type channels are produced in the same semiconductor using opposite dual-gating. It is possible to tune the photoconductive gain using a vertical electric field, so that the gain is constant with respect to the light intensity-a linear photoresponse, with a high responsivity of ≈2.5 × 104 A W-1 . Additionally, the 1/f noise of the device is kept at a low level under the opposite dual-gating due to the reduction of current and carrier fluctuation, resulting in a high detectivity of ≈2 × 1013 Jones in the linear photoresponse regime. The linear photoresponse and high performance of the dual-gate WSe2 phototransistor offer the possibility of achieving high-resolution and quantitative light detection with layered 2D semiconductors.

Sol–gel synthesis and physical characterization of novel MgCrO4-MgCu2O3 layered films and MgCrO4-MgCu2O3/p-Si based photodiode

Abstract: Crystalline MgCrO4-MgCu2O3 layered films prepared by the sol–gel process were deposited on glass and p-Si substrates. The films were characterized by XRD, SEM/HR-TEM, and UV–Vis​ optical spectroscopy. A photodiode based on MgCrO4-MgCu2O3/p-Si was assembled and electrically characterized in dark and illumination conditions. Structure and surface morphology investigations demonstrated that the MgCrO4-MgCu2O3 layered films exhibit a higher crystalline structure with a high surface area and a crystallite size of 14 nm. The layered films are opaque in the UV region and transmit light in visible and IR regions. The determined optical band gap is about 3.5 eV independent of the transition types — direct or indirect. In dark conditions, the noted values of the ideality factor, the barrier height, the series resistance of the assembled diode were 1.875, 1.097 eV and 46 . 72 k Ω , respectively. The recognized photocurrent action is driven by traps that lie inside the bandgap. These improvements in structural and optical properties can be attributed to the excellent internal rearrangement and the lower concentration of oxygen vacancy connected with Cr and Cu.

Thin-Film Photodetector Optimization for High-Performance Short-Wavelength Infrared Imaging

Abstract: In this letter, we present a small pixel pitch image sensor optimized for high external quantum efficiency in short-wavelength infrared (SWIR). Thin-film photodiodes based on PbS colloidal quantum dot (CQD) absorber allow us to exceed the spectral limitations of silicon’s absorption while maintaining the benefits of CMOS technology. By monolithically integrating PbS CDQ thin films with CMOS readout arrays, high-pixel density SWIR image sensors can be achieved. To overcome the remaining disadvantages of the CQD-based image sensors over their bulk III-V semiconductor counterparts (lower sensitivity and reduced linearity), the thin-film photodiode stack is adapted towards the used readout circuit. A prototype image sensor with a $768\times 512$ resolution of 5- $\mu \text{m}$ pitch pixels is fabricated by using a modified 130 nm CMOS process for readout IC, together with the new CQD thin-film photodiode on top. Thanks to the optimized photodiode stack and co-integration process, the prototype image sensor shows less than 5% linearity error while having 40% external quantum efficiency in SWIR, which enables acquisition of high-quality images.

Complex Optical Index of HgTe Nanocrystal Infrared Thin Films and Its Use for Short Wave Infrared Photodiode Design

Abstract: The limited investigations of the optical properties of HgTe nanocrystal (NC) thin films have reached a bottleneck for the electromagnetic design of devices. Using broadband ellipsometry, we determine the refractive index (n) and the extinction coefficient (k) for a series of HgTe NC films relevant for infrared sensing applications. Electromagnetic simulations reveal that the n value of HgTe NC thin films can conveniently be approximated by its mean spectral value n=2.35 ± 0.15. We then use this complex optical index to design a diode with (i) a reduced amount of Hg containing material (thin film < 150 nm) and (ii) a thickness of the device better-matched with the carrier diffusion length. We demonstrate that introducing an aluminum grating onto the transparent conductive electrode leads to an enhanced absorption while reinforcing the work-function difference between the two electrodes. Broadband (≈ 1 µm), non-polarized and strong absorption up to 100% is designed. This leads to a responsivity of 0.2 A.W-1 and a detectivity of 2x10 10 Jones for 2 µm cutoff wavelength at room-temperature, while the time response is as short as 110 ns.

A regioregular donor–acceptor copolymer allowing a high gain–bandwidth product to be obtained in photomultiplication-type organic photodiodes

Abstract: Obtaining a photomultiplication-type organic photodiode with a high gain–bandwidth product is challenging. We show that a newly designed regioregular polymer enables the formation of a highly oriented face-on structure with a low trap density, leading to a high EQE and a fast response time. As a result, a gain–bandwidth product of over 4 × 105 Hz is achieved.

Switching photodiodes based on (2D/3D) PdSe2/Si heterojunctions with a broadband spectral response

Abstract: Noble metal dichalcogenides (NMDs) are two-dimensional (2D) layered materials that exhibit outstanding thickness-dependent tunable-bandgaps that can be suitable for various optoelectronic applications. Here, we developed high-performance switching photodiodes based on mix-dimensional 2D palladium diselenide (PdSe2) and three-dimensional (3D) silicon (Si) heterojunctions with a broadband spectral response by a mechanical exfoliation technique. We studied the gate-tunable rectifying behavior of n-PdSe2/p-Si diodes employing an ionic liquid gate and achieved a maximum diode rectification ratio If/Ir up to ∼1.0 × 105 with the lowest value of ideality factor ∼1.22 (at Vtg = −2 V). At different temperatures (60 to 300 K), Zener tunneling and avalanche breakdown phenomena were detected at the junction of PdSe2–Si. These devices showed excellent self-driven photoresponses over broadband wavelengths from 400 to 1200 nm. The response speed of estimated is 9.2/17.3 μs, which represents a fast photoresponse. Moreover, in our devices, open-circuit voltage (VOC = 0.6 V) switching behavior is attained with the on/off state of the incident light. Moreover, these devices were attested for dynamic rectification, and this effectively rectified an input alternating-voltage sine wave signal to an output signal. The results of this study indicate that 2D PdSe2 can be employed for high-performance optoelectronic applications.

Single nanoflake-based PtSe2 p–n junction (in-plane) formed by optical excitation of point defects in BN for ultrafast switching photodiodes

Abstract: Here, novel lateral PtSe2 p–n junctions are fabricated based on the PtSe2/BN/graphene (Gr) van der Waals heterostructures upon the illumination of visible light via the optical excitation of the mid-gap point defects in hexagonal boron nitride (h-BN). A stable photo doping effect was achieved for tuning the polarity of PtSe2-based field-effect transistors (FETs). The constructed diodes display excellent rectifying performance, with a rectification ratio of up to ∼1.0 × 105 and an ideality factor of ∼1.3. Distinctive self-biased photovoltaic behavior was detected, specifically in the positive open-circuit voltage (Voc = 0.32 V) at zero source–drain current (Ids), and also the negative short-circuit current (Isc = 16.2 nA) at zero source–drain voltage (Vds) generated for the p–n diode state upon the illumination of incident light (600 nm, 40 mW cm−2). Moreover, output Voc switching behavior was achieved for the p–n diode state by switching the input light signal on and off, with a photoresponse over the broadband spectral range of 200–1200 nm. Various photovoltaic parameters were also measured. Also, using this elegant approach, homoinverters were fabricated that reached a maximum gain of ∼30 (VDD = 2 V). These findings pave the way to developing self-biased photovoltaic devices by exploiting 2D noble metal dichalcogenide materials.

Automatic Quality Assessments of Laser Powder Bed Fusion Builds from Photodiode Sensor Measurements

Abstract: While Laser powder bed fusion (L-PBF) machines have greatly improved in recent years, the L-PBF process is still susceptible to several types of defect formation. Among the monitoring methods that have been explored to detect these defects, camera-based systems are the most prevalent. However, using only photodiode measurements to monitor the build process has potential benefits, as photodiode sensors are cost-efficient and typically have a higher sample rate compared to cameras. This study evaluates whether a combination of photodiode sensor measurements, taken during L-PBF builds, can be used to predict measures of the resulting build quality via a purely data-based approach. Using several unsupervised clustering approaches build density is classified with up to 93.54% accuracy using features extracted from three different photodiodes, as well as observations relating to the energy transferred to the material. Subsequently, a supervised learning method (Gaussian Process regression) is used to directly predict build density with a RMS error of 3.65%. The study, therefore, shows the potential for machine-learning algorithms to predict indicators of L-PBF build quality from photodiode build measurements only. This study also shows that, relative to the L-PBF process parameters, photodiode measurements can contribute to additional information regarding L-PBF part quality. Moreover, the work herein describes approaches that are predominantly probabilistic, thus facilitating uncertainty quantification in machine-learnt predictions of L-PBF build quality.

Design and characterization of asymetrical super-lattice Si/4H-SiC pin photo diode array: a potential opto-sensor for future applications in bio-medical domain

Abstract: Photo-sensors are integral part of different bio-medical diagnostic equipment. Each type of bio-molecules possess unique spectral fingerprint in visible wavelength region of electro-magnetic spectrum. Now-a-days, the enhancement of quantum-efficiency and photo-responsivity of such bio-medical opto-sensors, for accurate identification of virus/anti-bodies in blood by optical means, is a big challenge to medical-device Engineers. The authors have addressed this issue in this research paper by proposing a novel structure of asymmetrical Si/4H-SiC super-lattice pin diode array for the development of high-sensitive visible light (300–800 nm) sensor on native substrate. The simulation experiment is carried out by developing a generalized large-signal quantum modified drift–diffusion simulator incorporating three different modes of carrier generation-recombination under light and dark conditions: avalanching, tunneling and photo-irradiation. The validity of the model has been established by comparing the simulation results with those of experimental observations. A good agreement between theory and experiment, under similar biasing conditions, establishes the validity of the developed model. The characteristics analysis depicts that the quantum efficiency of the designed single photo-sensor is ~ 65% within 400–700 nm wavelength region, whereas, the same enhances to nearly ~ 90% with a 3 × 3 photo-sensor array based on asymmetrical super-lattice single pin devices. In visible wavelength region, the simulated photo-sensors (both single and array) have demonstrated significant photo responsivity. The photo-responsivity values, at 500 nm wavelength of incident radiation, are observed to be 0.65 A/W for a single photo-diode and 0.85 A/W for a 3 × 3 combination of photo-diode array. This clearly establishes the potentiality of the asymmetrical super-lattice pin-array as a visible photo-sensor for future application in developing medical instruments. A comparative analysis of Si and Si/4H-SiC asymmetrical super-lattice photo-sensors establishes the superiority of the later as a high-sensitive visible light-sensor in terms of better photo-responsivity and quantum efficiency. To the best of authors’ knowledge, this is the first report on Si/4H-SiC super-lattice pin photo-sensor array in the visible range of optical irradiation. The experimental feasibility of the device and a proposed circuit for future bio-medical implementation are also incorporated in the present research-paper for further development.

Highly efficient self-powered perovskite photodiode with an electron-blocking hole-transport NiOx layer.

Abstract: Hybrid organic–inorganic perovskite materials provide noteworthy compact systems that could offer ground-breaking architectures for dynamic operations and advanced engineering in high-performance energy-harvesting optoelectronic devices. Here, we demonstrate a highly effective self-powered perovskite-based photodiode with an electron-blocking hole-transport layer (NiOx). A high value of responsivity (R = 360 mA W−1) with good detectivity (D = 2.1 × 1011 Jones) and external quantum efficiency (EQE = 76.5%) is achieved due to the excellent interface quality and suppression of the dark current at zero bias voltage owing to the NiOx layer, providing outcomes one order of magnitude higher than values currently in the literature. Meanwhile, the value of R is progressively increased to 428 mA W−1 with D = 3.6 × 1011 Jones and EQE = 77% at a bias voltage of − 1.0 V. With a diode model, we also attained a high value of the built-in potential with the NiOx layer, which is a direct signature of the improvement of the charge-selecting characteristics of the NiOx layer. We also observed fast rise and decay times of approximately 0.9 and 1.8 ms, respectively, at zero bias voltage. Hence, these astonishing results based on the perovskite active layer together with the charge-selective NiOx layer provide a platform on which to realise high-performance self-powered photodiode as well as energy-harvesting devices in the field of optoelectronics.

Planar Multilayered 2D GeAs Schottky Photodiode for High-Performance Visible-Near-Infrared Photodetection.

Abstract: Novel group IV - V 2D semiconductors (e.g., GeAs and SiAs) have arisen as an attractive candidate for broad-band photodetection and optoelectronic applications. This 2D family has a wide tunable band gap, excellent thermodynamic stability, and strong in-plane anisotropy. However, their photonic and optoelectronic properties have not been extensively explored so far. This work demonstrates a broadband back-to-back metal-semiconductor-metal (MSM) Schottky photodiode with asymmetric contact geometries based on multilayered 2D GeAs. The photodetector exhibited a Schottky barrier height (SBH) in the range of 0.40-0.49 eV. Additionally, it showed a low dark current of 1.8 nA with stable, reproducible, and excellent broadband spectral response from UV to optical communication wavelengths. The highest measured responsivity in the visible is 905 A/W at 660 nm wavelength and 98 A/W for 1064 nm near-infrared at an applied voltage of -3 V and zero back gate. Most notably, the planner configuration of this GeAs photodetector showed a low detector capacitance below 1.2 pf and low voltage operation (<1 V). The stability and broadband response of the device are promising for this 2D material's application in advanced optoelectronic devices.

Waveguide coupled III-V photodiodes monolithically integrated on Si

Abstract: The seamless integration of III-V nanostructures on silicon is a long-standing goal and an important step towards integrated optical links. In the present work, we demonstrate scaled and waveguide coupled III-V photodiodes monolithically integrated on Si, implemented as InP/In0.5Ga0.5As/InP p-i-n structure. The waveguide coupled devices show a dark current down to 0.048 A/cm2 at -1 V and a responsivity up to 0.2 A/W at -2 V. Using grating couplers centered around 1320 nm, we observed a cutoff frequency f3dB exceeding 70 GHz and data reception at 50 GBd with OOK and 4PAM. When operated in forward bias as light emitting diode, the devices emit light centered at 1550 nm. Furthermore, we also investigate the self-heating of the devices using scanning thermal microscopy and find a temperature increase of only ~15 K during the device operation as emitter, in accordance with thermal simulation results.