Weak Light Detection Research Articles

High-quality silicon-based perovskite photodetectors with the detectivity exceeding 7.5 × 1013 Jones

Considering the advantages of silicon-based microelectronic devices and the excellent photophysical properties of halide perovskites, silicon-based perovskites are expected to demonstrate great potential for application in the field of optoelectronic devices. In this paper, an antisolvent-assisted strategy is used to prepare MAPbBr3 perovskite microcrystals on silicon substrates, and dense, continuous, and smooth perovskite microcrystal thick films are further obtained after the hot-press treatment. Finally, an n-Si/perovskite thick film/carbon structure device is constructed which shows excellent photoresponsive performance with a responsivity of 11.7 A/W, a detectivity of 7.57 × 1013 Jones, and a linear dynamic range of 147 dB at 405 nm with a 0.5 V bias. Moreover, the device can respond to the light with its light intensity of as low as 2.14 × 10−6 mW cm−2, demonstrating excellent weak-light detection performance. This integration of silicon with the halide perovskites shows tremendous potential for applications in the field of semiconductor devices.

Ultra‐Fast Weak Light Detectors Based on van der Waals Stacked 2D Semiconductor/h‐BN Heterostructures

AbstractFast and sensitive detectors for weak light are crucial in various fields like real‐time monitoring, medical diagnosis, and astronomy. However, photodetectors using 2D materials face challenges in achieving both a low detection limit for weak light and fast response. Here, a vertical vdW graphene/indium selenide (InSe)/hexagonal boron nitride (h‐BN) heterostructure on a gold electrode is provided, demonstrating an ultra‐low detection limit of 47.4 nW cm−2 and an ultra‐fast response speed of 327 ns. Vertical photodetectors feature nanoscale channel length, thus reducing scattering and recombination of carriers. The high potential barrier of multilayer h‐BN effectively blocks carrier transport, resulting in ultra‐low dark current and minimal power dissipation. Additionally, enhanced light absorption in InSe by the metal‐insulator‐semiconductor structure improves the sensitivity to weak light detection. More importantly, the built‐in field at the graphene/InSe interface can promote the separation of photo‐generated carriers to improve the collection efficiency. These factors jointly reduce the detection limit and response time simultaneously for weak light. This vertical vdW heterostructure comprising a 2D semiconductor/h‐BN offers a solution to make the majority of 2D semiconductors applicable in ultra‐fast weak light detectors.

High-Sensitivity and Fast-Response Photomultiplication Type Photodetectors Based on Quasi-2D Perovskite Films for Weak-Light Detection.

Photovoltaic photodiodes often face challenges in effectively harvesting electrical signals, especially when detecting faint light. In contrast, photomultiplication type photodetectors (PM-PDs) are renowned for their exceptional sensitivity to weak signals. Here, an advanced PM-PD is introduced based on quasi 2D Ruddlesden-Popper (Q-2D RP) perovskites, optimized for weak light detection at minimal operating voltages. The abundant traps at the Q-2D RP surface capture charge carriers, inducing a trap-assisted tunneling mechanism that leads to the photomultiplication (PM) effect. Deep-lying trap states within the Q-2D RP bulk accelerate charge carrier recombination, resulting in an outstanding rise/fall time of 1.14/1.72 µs for the PM-PDs. The PM-PD achieves a remarkable response level of up to 45.89 AW-1 and an extraordinary external quantum efficiency of 14400% at -1V under an illumination of 1 µWcm- 2. The intrinsic high resistance of the Q-2D perovskite results in a low dark current, enabling an impressive detectivity of 4.23 × 1012 Jones based on noise current at -1V. Furthermore, the practical application of PM-PDs has been demonstrated in weak-light, high-rate communication systems. These findings confirm the significant potential of PM-PDs based on Q-2D perovskites for weak light detection and suggest new directions for developing low-power, high-performance PM-PDs for future applications.

Thermodynamically induced crystal restructuring to make CsPbCl3 single crystal films for weak light detection

Thermodynamically induced crystal restructuring to make CsPbCl3 single crystal films for weak light detection

Low-temperature fabrication of lead-free Ag2BiI5 perovskite photodetector with excellent weak light detection ability for accurate gesture recognition

In recent years, lead halide perovskites have been extensively researched in the optoelectronics field due to their excellent optical and electrical properties, while the inherent toxicity and instability of lead halide perovskites have hindered their commercialization. Stable, lead-free perovskites as a substitute of the Pb-based perovskites show great attention. Herein, the green antisolvent diethyl carbonate is introduced to realize the low-temperature fabrication of nontoxic perovskite Ag2BiI5. The Ag2BiI5 perovskite photodetector (PD) shows excellent performance with a detectivity of as high as 1.13 × 1013 Jones and a linear dynamic range (LDR) of 147 dB. Besides, the weak light with the light intensity of as low as 18.3 nW/cm2 can be detected by our PD. Moreover, the flexible PDs are also prepared with this low-temperature process, which shows good device performance with stable bending resistance characteristics. Based on the excellent optoelectronic properties of the Ag2BiI5 PDs, a gesture recognition system is built which can realize rapid and accurate gesture recognition under ordinary indoor light, with an accuracy of 98.35 %. Our research provides new insights for the development and application of green and environmentally friendly perovskite PD.

Enhancing large-area Geiger-mode avalanche photodiode performance through dynamic memristor quenching: a study on improving count rate, reducing jitter and mitigating afterpulsing

While the larger photosensitive area of Geiger-mode avalanche photodiodes (GmAPDs) enhances their detection range and signal collection, improving their utility in weak light detection, their practicality is limited by a long recovery time, high afterpulsing probability (AP) and excessive jitter. Utilizing a dynamic memristor as a quenching resistor, this research improves the count rate of a large-size GmAPD by 100× at an overvoltage of 2.5 V, compared with a fixed resistor-quenched GmAPD. Furthermore, at a photon pulse frequency of 1 MHz jitter time is reduced from 3.60 ns to 0.48 ns, and the afterpulsing probability is effectively mitigated from 30.88% to 8.58%.

Window size dependence of gain and bandwidth in avalanche photodiodes with multiple multiplication layers under near Geiger-mode operation

We consider avalanche photodiodes (APDs) functioning under near Geiger-mode operation for extremely weak light (single or several photons) detection, such as in LiDAR receivers. To meet such demands, APDs which simultaneously have a large active window size, moderate bandwidth (∼GHz), and high internal gain (responsivity), are highly desired. However, it is difficult to design APDs capable of meeting the afore-mentioned performance requirements due to the intrinsic limitations of the gain-bandwidth product (GBP). In this work, we demonstrate that the GBP bottleneck in the APDs can be overcome by using multiple (3) In0.52Al0.48As based multiplication (M-) layers with a thick In0.53Ga0.47As absorber (2 µm). Moreover, the characteristic invariant 3-dB bandwidth in our APDs, from low to an extremely high operation gain, becomes more pronounced with an increase of its active window diameter (40 to 200 µm). This characteristic makes it very attractive for collecting weak light in free space as is required for LIDAR receiver applications. Comparison shows that the 200 µm APD exhibits a higher 0.9 Vbr responsivity (15 vs. 7 A/W), larger maximum gain (460 vs. 110), and higher GBP (468 vs. 131 GHz) than does the 40 µm reference sample and can sustain a constant 3-dB bandwidth (1.4 GHz) over a wide range of operation gains (10 to 460). The dependence of the APD performance on the window size can be attributed to the influence of the surface states on the edge of the etched mesa. Here, we further demonstrate a backside-illuminated structure with a flip-chip bonding package which minimizes this phenomenon in small APDs ensuring high-speed performance. Compared with the top-illuminated reference samples, the flip-chip bonding packaged device shows a further enhancement of the responsivity (10.7 vs. 7 A/W), 3-dB bandwidth (4.1 vs. 3.9 GHz), and saturation current (4.25 vs. 3.6 mA). The excellent static and dynamic performance of our flip-chip APD in turn leads to an unprecedented high velocity sensitivity (5 µm/sec) and superior quality 4-D FMCW LiDAR images compared to that obtainable with p-i-n-based or top-illuminated reference devices with the same small active window size (40 µm).

Weak signal detection based on pulse width counting method for underwater wireless optical communication with an analog mode PMT detector

This work proposes a weak signal detection method based on pulse width counting (PWC) for the on-off keying (OOK) underwater wireless optical communication (UWOC) system with an analog mode photomultiplier tube (PMT) detector. The signal output model of the analog mode PMT in weak light communication and the influence of pulse overlap are investigated. We experimentally evaluate the proposed algorithm under different sampling rates, detection thresholds, data rates as well as received optical powers (ROPs), and compare the performance of the proposed approach with that of pulse amplitude detection and pulse peak counting. A 10-Mbps OOK UWOC link is realized with a sensitivity of -71.5 dBm in a 7-meter tank, which is 1.1-dB and 3.8-dB lower than that of pulse peak counting (PPC) and pulse amplitude detection (PAD) methods, respectively, and the total link attenuation is 94.8 dB. This system utilizes the analog mode PMT with larger dynamic range than photon-counting mode PMT to achieve weak light signal detection, which benefits design long-range UWOC systems.

Imaging ultra-weak UV light below 100 pW cm-2 using a 4H-SiC photodetector with an Al2O3 interfacial layer.

Weak light detection is crucial in various practical applications such as night vision systems, flame monitoring, and underwater operations. Decreasing the dark current of a photodetector can effectively mitigate noises, consequently enhancing the signal-to-noise ratio and overall weak light detection performance. Herein, we demonstrate a 4H-SiC UV photodetector capable of detecting extremely weak UV light. This device comprises a photosensitive layer of 4H-SiC, two TiN electrodes and an atomically thin Al2O3 interfacial layer between TiN and the C surface of 4H-SiC. Under 360 nm UV light illumination, the proposed Al2O3 device demonstrates an ultra-low dark current of 18 fA, possibly benefiting from the effective passivation of interfacial carriers, and a boosted photo-to-dark current ratio of 6.7 × 107. Consequently, it achieves a weak-light detection limit as low as 31.8 pW cm-2, significantly outperforming the control device lacking Al2O3. When compared to previously reported SiC photodetectors, our Al2O3 device boasts an exceptional large linear dynamic range of 172 dB. Leveraging this, we construct a photodetector array capable of clearly imaging an object under ultra-weak light illumination below the 100 pW cm-2 level. The proposed photodetector represents a significant advancement in the development of highly sensitive image sensors for weak light detection.

Room-Temperature Growth of Square-Millimeter Single-Crystalline Two-Dimensional Metal Halides on Silicon.

Silicon is the cornerstone of electronics and photonics. In this context, almost all integrated devices derived from two-dimensional (2D) materials stay rooted in silicon technology. However, as the growth substrate, silicon has long been thought to be a hindrance for growing 2D materials through bottom-up methods that require high growth temperatures, and thus, indirect routes are usually considered instead. Although promising growth of large-area 2D materials on silicon has been demonstrated, the direct growth of single-crystalline materials using low-thermal-budget synthesis methods remains challenging. Here, we report the room-temperature growth of millimeter-scale single-crystal 2D metal halides on silicon substrates with a hydroxyl-terminated surface. Theoretical calculations reveal that the activation energy for surface diffusion can be reduced by an order of magnitude by terminating the surface with hydroxyl groups, from which on-silicon growth is greatly facilitated at room temperature and enables a 4-order-of-magnitude increase in area. The high quality and uniformity of the resulting single crystals are further evidenced. The optoelectronic devices employing the as-grown materials show an ultralow dark current of 10-13 A and a high detectivity of 1013 Jones, thereby corroborating a weak-light detection ability. These results would point to a rich space of surface modulation that can be used to surmount current limitations and demonstrate a promising strategy for growing 2D materials directly on silicon at room temperature to produce large single crystals.

Realizing Weak Light Detection in a 2D Dielectric Switching Hybrid Perovskite Incorporating Dimethylamine

Abstract2D organic–inorganic hybrid perovskites (OIHPs) are regarded as potential candidates for the advancement of multifunctional phase‐transition materials due to their ability to integrate flexible functionality and superior electronic features from both organic and inorganic components. However, the development of 2D OIHPs with dielectric switches and weak light detection capability that are crucial for high‐resolution sensing and imaging, remains challenge. Herein, a novel 2D OIHP BDADMAPb2Br7 (1, BDA = 1,4‐butanediamine and DMA = dimethylamine) is presented, featuring a 2D Dion–Jacobson (DJ) bilayered structure incorporated with secondary amine. Upon heating and cooling cycles, 1 demonstrates long‐term reversible dielectric switching properties at 328 K. Meanwhile, 1 also shows compelling semiconductor characteristics, including a low dark current of 2.87 × 10−11 A (10 V), a large switching ratio of 4 × 103, and a high detectivity of 1.3 × 1012 Jones. In addition, the photodetector based on 1 exhibits an excellent weak light detection ability of 340 nW cm−2 at 405 nm. Such a 2D OIHP demonstrates a novel platform for creating multifunctional materials and significantly promotes the development of integrated devices.

Sensitive Filter‐Free Narrowband Infrared Photodetectors for Weak Light Detection and Ranging

AbstractLight detection and ranging (Lidar), which utilizes scattered near‐infrared (NIR) light to identify objects, has shown great potential in remote sensing, autonomous driving, robotic vision, etc. However, the intensity of the scattered NIR light is significantly reduced, placing stringent demands on the selectivity and fast response of the sensing. Even though optical filters can be used to select weak signals, the photon losses arising from additional interfaces are inevitable, thus reducing the signal‐to‐noise ratio (SNR). In this work, a series of organic narrowband photodetectors are constructed with tunable and selective responses from 700 to 950 nm with a minimum full‐width‐at‐half‐maximum (FWHM) of ≈30 nm. To enhance response sensitivity and speed, delicate and compact photodiode architecture is applied through comprehensive device engineering. As a result, the detectors possess a sensitive response to weak NIR light with a detection limit of 3 nW, and response rise time (τr) and decay time (τd) of ≈24 ns and ≈1.3 µs, respectively. Moreover, a proof‐of‐concept Lidar based on these organic photodetectors is demonstrated with a distance resolution of ≈10 cm, which further confirms the great potential in practical application.

P(VDF-TrFE) interlayer enables high performance of Sb2Se3 photodetectors

Antimony selenide (Sb2Se3) has been extensively studied in photodetectors (PDs) for its extraordinary photoelectric properties. In this study, we report a new attempt to apply ferroelectric material P(VDF-TrFE)) in Sb2Se3 PDs. The P(VDF-TrFE) thin films were coated on Sb2Se3, which effectively improved the interface quality between the Sb2Se3 thin films and the C electrode, leading to a smaller leakage current. Moreover, due to the ferroelectric effect of P(VDF-TrFE), the remanent polarization enhances the separation and transmission of photogenerated carriers, which significantly improves the photoelectric performance of Sb2Se3 PDs. Experimental results show that the insertion of P(VDF-TrFE) enables the device to have a low dark current (from 2.0 × 10−3 to 1.6 × 10−4 μA) and ultra-high On/Off ratio (from 5.06 × 102 to 1.26 × 104). In addition, the resulting device exhibits weak light detection ability with a photo-responsive at a weak light of 5 × 10−6 W cm−2.

Photoresponse Enhancement in MAPbI3/Si Heterojunction Through P(VDF‐TrFE) Doping and Introducing Pyro‐Phototronic Effect

AbstractThe photovoltaic effect and pyro‐phototronic effect offer a promising approach to enhance self‐powered photodetectors (PDs) performance. However, further investigation is warranted to explore the performance improvement, the impact of pyroelectric effect, and the underlying coupling mechanism. In this study, heterojunction PDs consisting of ITO/CH3NH3(MA)PbI3:P(VDF‐TrFE)/Si are prepared, with P(VDF‐TrFE) concentration varying from 0 to 1 wt.%. The results reveal that the concentration of P(VDF‐TrFE) has a significant impact on the photovoltaic response, with the optimal concentration being 0.8 wt.%. The PD displays a broadband response (405–1064 nm) at zero bias, peaking at 780 nm. Furthermore, the introduction of P(VDF‐TrFE) significantly enhances the responsivity (R) and detectivity (D), resulting in a remarkable increase of 5814%. The values of R and D reach 1.93 × 104 V W−1 and 1.99 × 1012 Jones, respectively. Moreover, the PD demonstrates an ultrafast response time of 81.6/208 µs. Additionally, the pyro‐phototronic effect extends the response wavelength to 1550 nm, surpassing the spectral limit of the heterojunction. Importantly, the heterojunction exhibits improved weak light detection ability. At 6.37 µW cm−2 intensity, R and D show an impressive increase of 21 683%, reaching 8.99 × 104 V W−1 and 9.3 × 1013 Jones, respectively.

Dark Current Reduction and Performance Improvements in Graphene/Silicon Heterojunction Photodetectors Obtained Using a Non-Stoichiometric HfOx Thin Oxide Layer.

Graphene/silicon heterojunction photodetectors suffer from a high dark current due to the high surface states and low barrier height at the interface, which limits their application. In this study, we introduce an HfOx interfacial layer via magnetron sputtering to address this issue. With this new structure, the dark current is reduced by six times under a bias voltage of -2 V. Under 460 nm illumination, the responsivity is 0.228A/W, the detectivity is 1.15 × 1011 cmHz1/2W-1, and the noise equivalent power is 8.75 × 10-5 pW/Hz1/2, demonstrating an excellent weak light detection capability. Additionally, the oxygen vacancies in the HfOx interfacial layer provide a conductive channel for charge carriers, resulting in a 2.03-fold increase in photocurrent and an external quantum efficiency of 76.5%. The photodetector maintains good photoresponse ability at a low bias voltage. This work showcases the outstanding performance of HfOx films as interfacial layer materials and provides a new solution for high-performance photodetectors, as well as a new path to improve the photovoltaic conversion efficiency of solar cells.

Interfacial Engineering for Photomultiplication Type Organic Photodetectors with Signal‐Noise‐Ratio Over 89 000

AbstractPhotomultiplication type organic photodetectors (PM‐OPDs) exhibit obvious superiority in weak light detection due to their low dark current density (JD) and large photo‐induced current density (JPI). The JD is one of the important parameters that influences light detection sensitivity of PM‐OPDs, how to effectively suppress the JD is a great challenge to improve the performance of PM‐OPDs. In this work, the JD of PM‐OPDs can be suppressed by employing PTAA or doped‐PTAA as the interfacial layer replacing PEDOT:PSS layer. The PM‐OPDs with PTAA layer exhibit a low JD of 2.3 × 10−7 A cm−2 under −6 V bias, which is much smaller than 1.4 × 10−6 A cm−2 for PM‐OPDs with PEDOT:PSS layer. The small molecule DRCN5T is incorporated into PTAA to further passivate surficial defects of PTAA films, which is conducive to reducing the leakage current of PM‐OPDs. The optimal PM‐OPDs exhibit rather low JD of 8.4 × 10−8 A cm−2 under −6 V bias, as well as external quantum efficiency (EQE) of 31700% and specific detectivity (D*) of 1.2 × 1013 Jones at 370 nm. The signal‐noise‐ratio of optimal PM‐OPDs arrives to 89600 under −4.5 V bias under white light illumination with intensity of 1.5 mW cm−2.

Tailoring performance of perovskite-based tunneling photodetector for portable monitoring of ultraviolet radiation risk

Portable sensing systems have a broad application prospect in the field of personal healthcare via continuous monitoring of surroundings. Ultraviolet (UV) light, deemed to be a main inducement of skin-related cancers, calls for the development of UV detectors with properties of high sensitivity and portability. Herein, we constructed a CsPbCl3 film-based tunneling UV sensor (CTUS) based on the photo-induced tunneling mechanism. By optimizing the thickness of the tunneling layer inserted through an atomic layer deposition process, dark current of the CTUS was suppressed by three orders of magnitude, thus obtaining a salient UV detecting performance (ultralow dark current of 100 pA, high responsivity of 285 mA/W, broad linear dynamic range of 95 dB, fast response time of 2.1 μs, and weak light detection limit of 150 nW), which is comparable to the commercial Si-based PIN-type UV detectors. A UV wristband was further built by merging the CTUS with a self-designed flexible printed circuit board. Co-assisted by a self-developed APP, real-time and continuous monitoring of sun radiation to prevent diseases due to excessive sunburn was demonstrated. The proof-of-concept system will pave the way for portable device development, thus bridging the gap between technology innovation and real life.

Solution-Processed Sb2S3-Based Heterojunction for Self-Powered Broad Band Weak Light Detection.

Antimony sulfide (Sb2S3) has recently regained the attention of photovoltaic researchers as a promising solar absorber; however, its application for the detection of white light remains relatively unexplored. Herein, we report on the self-powered heterojunction photodetector based on a device-grade Sb2S3 film made at low temperature with solution processing. The Sb2S3 absorber film was prepared by single-step spin coating of a novel precursor ink using antimony trichloride as the antimony source along with the low melting thioacetamide as the sulfur source in 2-methoxyethanol, a low boiling environmentally friendly solvent. A simple TiO2/Sb2S3 heterojunction device made by using the film shows a power conversion efficiency of 1.22% without any hole transporting layer. Interestingly, the self-powered photodetector performance of the device under white light exhibits a high on/off ratio of 2.2 × 104 under 1 sun illumination. Moreover, this optical filter-free ultraviolet-visible absorbing near-infrared blind photodetector is equally capable of detecting both strong and weak white light, with a response time of 98 ms. Further, an example of the real-life application of the device is successfully demonstrated by constructing a weak light-detecting sunlight tracking system.

High-performance self-powered ultraviolet photodetector based on a ZnO/CuPc inorganic/organic heterojunction.

A self-powered photodetector (PD) based on n-type ZnO/p-type small-molecule copper(ii) phthalocyanine (CuPc) inorganic/organic heterojunction film deposited on FTO substrate was constructed by simple solution spin-coating and thermal evaporation technology. The designed heterojunction device exhibits typical photoresponse behavior under zero bias, indicating that the device possesses a self-powered characteristic. This may benefit from the formation of a built-in electric field in the heterojunction, which can effectively separate electron-hole pairs. Specifically, the optimal performances of the device appear at a wavelength of 365 nm and light intensity of 0.03 mW cm-2, achieving on/off ratio of ∼245.88 (29.88), responsivity (Rp) of ∼227.11 mA W-1 (0.39 mA W-1), detectivity (D*) of ∼7.63 × 1011 Jones (∼7.53 × 109 Jones) and EQE of ∼77.23% (0.14%) at +2 V (0 V) bias voltage. In addition, the device has potential application in weak light detection. Therefore, the construction of inorganic/organic heterojunctions may provide a feasible strategy for the development of high-performance, self-powered and wavelength-selective PDs.

Self-Powered, Low-Dark-Current, High-Detectivity CsPbBr3 Nanowire Photodetectors with Excellent Weak-Light Detection Ability

In recent years, all-inorganic CsPbBr3 perovskite materials have shown significant progress in photonic device research due to their straightforward fabrication, cost-effectiveness, efficient photoelectric conversion and stability. However, the low solubility...