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An optimized Graphene/4H-SiC/Graphene MSM UV-photodetector operating in a wide range of temperature
摘要： In this paper, .an accurate analytical model has been developed to optimize the performance of an Interdigitated Graphene Electrode/p-silicon carbide (IGE/p-4H-SiC) Metal semiconductor fitness function for the multi objective optimization (MOGA) approach. The optimized sensitivity and speed performances was executed. Our results confirm the excellent ability of the suggested Graphene electrode system to decrease the unwanted shadowing effect. A responsivity of 238 μA/W was obtained under 325-nm illumination compared to the 16.7 μA/W for the conventional Cr-Pd/p-SiC PD. A photocurrent to- dark-current ratio (PDCR) of 5.75 × 105 at 300K and 270 at 500K was distinguished. The response time was found to be around 14 μs at 300K and 54.5 μs at 500K. Furthermore, the developed model serves as a fitness function to recognize the IGE formalism pattern which permits the enhancement of the performance of the proposed Gr/4H-SiC IE MSM PD using MOGA-based technique. The achieved results indicate that the suggested design methodology not only permits to realize a superior compromise amid responsivity and response time, but also shed light on the proposed device’s ruggedness under high temperature conditions. This opens the way to realize ultra-sensitive, high-speed SiC optoelectronic devices for extremely high temperature applications.
关键词： Analytical Model,UV photodetector,Graphene,MOGA approach,4H-SiC,interdigitated electrodes
更新于2025-09-23 15:19:57
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A high-sensitivity, fast-response, rapid-recovery UV photodetector based on p-GaN/NiO nanostructures/n-GaN sandwich structure
摘要： A high-performance p-GaN/NiO nanostructures/n-GaN ultraviolet (UV) sandwich structure photodetector was fabricated that was composed of NiO nanostructures grown on n-GaN and a p-GaN film layer. The device based on the GaN p-GaN/NiO nanostructures/n-GaN sandwich structure showed a high responsivity and fast response. This study provides a method to fabricate high-response UV photodetectors for GaN-based materials by combining them with metal oxide nanostructures.
关键词： Sandwich structure,GaN,NiO,Photodetector
更新于2025-09-23 15:19:57
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The role of CdS doping in improving SWIR photovoltaic and photoconductive responses in solution grown CdS/PbS heterojunctions
摘要： Low cost Short Wavelength Infrared (SWIR) photovoltaic (PV) detectors and solar cells are of very great interest, yet the main production technology today is based on costly epitaxial growth of InGaAs layers. In this study, layers of p-type, quantum confined (QC) PbS nano-domains (NDs) structure that were engineered to absorb SWIR light at 1550nm (Eg=0.8 eV) were fabricated from solution using the Chemical Bath Deposition (CBD) technique. The layers were grown on top of two different n-type CdS intermediate layers (Eg=2.4 eV) using two different CBD protocols on Fluoride Tin Oxide (FTO) substrates. Two types of CdS/PbS heterojunction were obtained to serve as SWIR PV detectors. The two resulting devices showed similar photoluminescence behavior, but a profoundly different electrical response to SWIR illumination. One type of CdS/PbS heterojunction exhibited a PV response to SWIR light, while the other demonstrated a photo-response to SWIR light only under an applied bias. To clarify this intriguing phenomenon, and since the only difference between the two heterojunctions could be the doping level of the CdS layer, we measured the doping level of this layer by means of the surface photo voltage (SPV). This yielded different polarizations for the two devices, indicating different doping levels of the CdS for the two different fabrication protocols, which was also confirmed by Hall Effect measurements. We performed current voltage measurements under super bandgap illumination, with respect to CdS, and got an electrical response indicating a barrier free for holes transfer from the CdS to the PbS. The results indicate that the different response does, indeed, originate from variations in the band structures at the interface of the CdS/PbS heterojunction due to the different doping levels of the CdS. We found that, unlike solar cells or visible light detectors having similar structure, in SWIR photodetectors, a type I heterojunction is formed having a barrier at the interface that limits the injection of the photo-exited electrons from the QC-PbS to the CdS side. Higher n-doped CdS generates a narrow depletion region on the CdS side, with a spike like barrier that is narrow enough to enable tunneling current, leading to a PV current. Our results show that an external quantum efficiency (EQE) of ~2% and an internal quantum efficiency (IQE) of ~20% can be obtained, at zero bias, for CBD grown SWIR sensitive CdS/PbS-NDs heterojunctions.
关键词： CBD,CdS/PbS heterojunction,SWIR photodetector,PbS NDs
更新于2025-09-23 15:19:57
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One-step fabrication of 1D p-NiO nanowire/n-Si heterojunction: development of self-powered ultraviolet photodetector
摘要： Even though there are reports on NiO-p/Si-n based photodetector, work along 1D NiO/Si self-powered photodetector remains unexplored. 1D materials offer better electron mobility and can provide ballistic transport channel, which helps in achieving high responsivity. In this work, direct single-step deposition of p-type NiO nanowires on n-type Si as a self-powered photodetector was successfully fabricated by engaging simple electrospinning technique. The structural properties as observed from XRD indicate highly crystalline NiO nanowires and FESEM images revealed 60 ~75 nm diameter with uniform distribution. Growth of nanowires by using stimuli polymer and its completely removal at high temperature was confirmed using TGA and XPS analysis. The responsivity of the fabricated photodetector was calculated to be 9.1 mA W-1 at zero bias, which can be attributed to the p-type NiO interface with the n-type Silicon, which creates an internal electrical field thereby assisting in the effective separation of the photogenerated carriers. Further, under illumination, at zero bias, the photogenerated current still exists suggesting a generation of internal voltage, which makes the fabricated device as self-powered. This fabrication method will enhance the photodetection properties, and it can be implemented in the fields of optoelectronic devices, sensors, and flexible electronics.
关键词： Electrospinning,NiO nanowires,1D material,Self-powered photodetector
更新于2025-09-23 15:19:57
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HBN-Encapsulated, Graphene-based, Room-temperature Terahertz Receivers, with High Speed and Low Noise
摘要： Uncooled terahertz photodetectors (PDs) showing fast (ps) response and high sensitivity (noise equivalent power (NEP) < nW/Hz1/2) over a broad (0.5?10 THz) frequency range are needed for applications in high-resolution spectroscopy (relative accuracy ～10?11), metrology, quantum information, security, imaging, optical communications. However, present terahertz receivers cannot provide the required balance between sensitivity, speed, operation temperature, and frequency range. Here, we demonstrate uncooled terahertz PDs combining the low (～2000 kB μm?2) electronic specific heat of high mobility (>50 000 cm2 V?1 s?1) hexagonal boron nitride-encapsulated graphene, with asymmetric field enhancement produced by a bow-tie antenna, resonating at 3 THz. This produces a strong photo-thermoelectric conversion, which simultaneously leads to a combination of high sensitivity (NEP ≤ 160 pW Hz?1/2), fast response time (≤3.3 ns), and a 4 orders of magnitude dynamic range, making our devices the fastest, broad-band, low-noise, room-temperature terahertz PD, to date.
关键词： terahertz,thermoelectric effect,graphene,photodetector
更新于2025-09-23 15:19:57
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High Operation Stability and Different Sensing Mechanisms in Graphene Oxide Gel Photodetectors Utilizing a Thin Polymeric Layer
摘要： We report a significant improvement in the operational stability and photosensitivity of an interdigitated photodetector using a hybrid sensing material based on a reduced graphene oxide gel (femtogel) and poly methyl methacrylate (PMMA). By coating the reduced graphene oxide photodetector with a protective layer of PMMA, a noticeable current stability is achieved, either during a sweep or fixed voltage, compared to an unprotected photodetector. A bolometric-effect sensing mechanism was observed in the unprotected photodetector, whereas the hybrid PMMA/femtogel photodetector displayed a photovoltaic-effect sensing mechanism. This change in the sensing mechanism of the graphene-based device, as a result of encapsulating the sensing area using a polymeric thin layer, is reported for the first time. Moreover, a higher and reliable sensitivity to the low-power illumination source was observed in the hybrid PMMA/femtogel photodetector. This study provides an avenue for engineering the performance and reliability of graphene oxide photodetectors that operate in an ambient environment in order to solve the current bottleneck issue, resulting from lack of reliability, in commercializing these material.
关键词： Bolometric effect,Sensing mechanism,PMMA,Photodetector,Graphene oxide,Graphene gel
更新于2025-09-23 15:19:57
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An Improved Room-Temperature Silicon Terahertz Photodetector on Sapphire Substrates
摘要： We design and fabricate a good performance silicon photoconductive terahertz detector on sapphire substrates at room temperature. The best voltage responsivity of the detector is 6679 V/W at frequency 300 GHz as well as low voltage noise of 3.8 nV/Hz1/2 for noise equivalent power 0.57 pW/Hz1/2. The measured response time of the device is about 9 ??s, demonstrating that the detector has a speed of >110 kHz. The achieved good performance, together with large detector size (acceptance area is 3 ??m×160 ??m), simple structure, easy manufacturing method, compatibility with mature silicon technology, and suitability for large-scale fabrication of imaging arrays provide a promising approach to the development of sensitive terahertz room-temperature detectors.
关键词： terahertz,room-temperature,sapphire substrates,silicon,photodetector
更新于2025-09-23 15:19:57
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Self-Powered Filterless Narrow-Band pa??n Heterojunction Photodetector for Low Background Limited Near-Infrared Image Sensor Application
摘要： Photonic detection with narrow spectrum selectivity is very important to eliminate the signal from obtrusive light, which can improve the anti-interference ability of the infrared imaging system. While self-driving effect inherent to p-n junction is very attractive in optic-electronic integration, the application of p-n junction in narrow-band photodetector is limited by the usual broad absorption range. In this work, a self-powered filterless narrowband near-infrared photodetector based on CuGaTe2/silicon p-n junction was reported. The as-fabricated photodetector exhibited typical narrow-band response which shall be ascribed to the slightly smaller bandgap of Si than CuGaTe2 and the restricted photocurrent generation region in the p-n heterojunction by optimizing CuGaTe2 thickness. It is observed that when the thickness of CuGaTe2 film is 143 nm, the device exhibits a response peak centered around 1050 nm with a full-width at half-maximum of ~118 nm. Further device analysis reveals a specific detectivity of ~1012 Jones and a responsivity of 114 mA/W under 1064 nm illumination at zero bias. It was also found that image system based on the narrowband CuGaTe2/Si photodetector showed high noise immunity for its spectral selective characteristics.
关键词： p-n heterojunction,near infrared light,image sensing,spectral selectivity,narrow band photodetector
更新于2025-09-23 15:19:57
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Controlled Growth of Large-scale Uniform 1Ta?2 MoTe2 Crystals with Tunable Thickness and its photodetector application
摘要： The monoclinic phase 1T′ MoTe2 exhibits inversion symmetry as an anisotropic semi-metal, dictating its interesting quantum transport phenomenon and other novel physical properties. However, large-scale controlled growth of uniform MoTe2 crystal still remain great challenges, hindering its further fundamental research and applications for novel devices. Here, we report a modified growth method to synthesizing few-layer 1T′ MoTe2 crystals with large-scale uniformity by assistance of molecular sieves. The theoretical simulations demonstrated that due to the temperature-dependent formation energies of different edges, the edge of (010) orientation shown high thermodynamic stability than the (100) orientation, and results in the anisotropic growth behavior of 1T' MoTe2 while the temperature changes. The photoresponse of tri-layer 1T' MoTe2 based devices shown a wide spectrum reponse from 532 nm to 1550 nm. The photo-response time of 1T' MoTe2 crystal demonstrate that it supposes to be the synergistic mechanism of photo-conductive and photo-radiatation effect. Our findings not only provide a method for the controllable growth of anisotropic two-dimensional materials at wafer scale, but also explore a wide spectrum photodetector with the MoTe2-based device.
关键词： anisotropic growth,1T′ MoTe2,wide spectrum photodetector,molecular sieves
更新于2025-09-23 15:19:57
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Single GaAs nanowire based photodetector fabricated by dielectrophoresis
摘要： Mechanical manipulation of nanowires (NWs) for their integration in electronics is still problematic because of their reduced dimensions, risking to produce mechanical damage to the NW structure and electronic properties during the assembly process. In this regard, contactless NW manipulation based methods using non-uniform electric fields, like dielectrophoresis (DEP) are usually much softer than mechanical methods, offering a less destructive alternative for integrating nanostructures in electronic devices. Here, we report a feasible and reproducible dielectrophoretic method to assemble single GaAs NWs (with radius 35–50 nm, and lengths 3–5 μm) on conductive electrodes layout with assembly yields above 90% per site, and alignment yields of 95%. The electrical characteristics of the dielectrophoretic contact formed between a GaAs NW and conductive electrodes have been measured, observing Schottky barrier like contacts. Our results also show the fast fabrication of diodes with rectifying characteristics due to the formation of a low-resistance contact between the Ga catalytic droplet at the tip of the NW when using Al doped ZnO as electrode. The current-voltage characteristics of a single Ga-terminated GaAs NW measured in dark and under illumination exhibit a strong sensitivity to visible light under forward bias conditions (around two orders of magnitude), mainly produced by a change on the series resistance of the device.
关键词： chemical beam epitaxy,optoelectronics,dielectrophoresis,nanowire assembly,GaAs nanowire photodetector,nanofabrication
更新于2025-09-23 15:19:57