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Detectors|86 Article(s)
Fast-Response Vertical-Structure Two-Dimensional Perovskite Photodetector
Haibo Zhang, Ting Ji, Jiayu He, Linlin Shi, Guohui Li, and Yanxia Cui
A vertical-structure photodetector based on two-dimensional perovskite (PEA)2(MA)4Pb5I16[PEA is C6H5(CH2)NH3, MA is CH3NH3] is fabricated and its property is analyzed. The photocurrent of the device reaches a maximum when the thickness of the two-dimensional perovskite thin film is 280 nm, while at 500 nm, the external quantum efficiency reaches 90%, the responsivity reaches 0.37 A/W, and the detectivity reaches 3.4×1012 Jones(1 Jones=1 cm?Hz1/2/W). The response time of the device does not continue to decrease as the thickness of two-dimensional perovskite thin film decreases, but reaches a minimum at the thickness of 80 nm due to the effect of carrier transit time and the quality of perovskite thin film. By fixing the thickness of the two-dimensional perovskite film at 80 nm, we finally achieve a response time of 113 ns by reducing the effective area of the device. This work is of great significance to promote the development of low-cost and fast-response photodetectors. A vertical-structure photodetector based on two-dimensional perovskite (PEA)2(MA)4Pb5I16[PEA is C6H5(CH2)NH3, MA is CH3NH3] is fabricated and its property is analyzed. The photocurrent of the device reaches a maximum when the thickness of the two-dimensional perovskite thin film is 280 nm, while at 500 nm, the external quantum efficiency reaches 90%, the responsivity reaches 0.37 A/W, and the detectivity reaches 3.4×1012 Jones(1 Jones=1 cm?Hz1/2/W). The response time of the device does not continue to decrease as the thickness of two-dimensional perovskite thin film decreases, but reaches a minimum at the thickness of 80 nm due to the effect of carrier transit time and the quality of perovskite thin film. By fixing the thickness of the two-dimensional perovskite film at 80 nm, we finally achieve a response time of 113 ns by reducing the effective area of the device. This work is of great significance to promote the development of low-cost and fast-response photodetectors.
Laser & Optoelectronics Progress
- Publication Date: Mar. 10, 2024
- Vol. 61, Issue 5, 0504003 (2024)
Reconstructive Optical Spectrometer Using Perovskite Filter Arrays
Qichuan Tan, Peng Zeng, and Zheqi Yang
The optical spectrometer, an instrument used to detect and analyze spectra with various wavelength components of incident light, has a growing demand for applications in fundamental research, industrial production and daily life. Conventional spectrometers based on precise optical dispersion components usually necessitate large volume and weight, which hardly meet the trend of miniaturization and low cost for diverse applications. We realize a filter-array-based computational reconstructive optical spectrometer through combining a series Cs0.1MA0.9PbX3 (X is Cl, Br, I) perovskite materials with different visible light absorption characteristics prepared by spin coating method and complementary metal oxide semiconductor sensor. Considering the spectral response of the perovskite film array, the non-negative Tikhonov regularization method is used to reconstruct the spectra. Finally, the designed optical spectrometer is tested and verified, which exhibits a spectral resolution of 27 nm at 500 nm wavelength and achieves a certain spectral resolution within the visible range. The optical spectrometer, an instrument used to detect and analyze spectra with various wavelength components of incident light, has a growing demand for applications in fundamental research, industrial production and daily life. Conventional spectrometers based on precise optical dispersion components usually necessitate large volume and weight, which hardly meet the trend of miniaturization and low cost for diverse applications. We realize a filter-array-based computational reconstructive optical spectrometer through combining a series Cs0.1MA0.9PbX3 (X is Cl, Br, I) perovskite materials with different visible light absorption characteristics prepared by spin coating method and complementary metal oxide semiconductor sensor. Considering the spectral response of the perovskite film array, the non-negative Tikhonov regularization method is used to reconstruct the spectra. Finally, the designed optical spectrometer is tested and verified, which exhibits a spectral resolution of 27 nm at 500 nm wavelength and achieves a certain spectral resolution within the visible range.
Laser & Optoelectronics Progress
- Publication Date: Mar. 10, 2024
- Vol. 61, Issue 5, 0504002 (2024)
Light Absorption Performance of Graphene Photodetector Based on Localized Surface Plasmon Resonance Effect
Qilin Xu, and Kexue Sun
In order to solve the problem of low light absorption of silicon nanowire photodetector, we construct a hexagonal silicon nanowire structure of photodetector. We cover the structure with zero-bandgap graphene and add Au grating at the same time, and finally use COMSOL software to model and analyze the structure. It is shown that in the optical band range between 0.5 μm and 1.5 μm, the graphene coverage and the Au grating can effectively enhance the light absorption performance of the device. What is more, the thickness of both graphene and Au grating has an effect on the performance of the device. In order to solve the problem of low light absorption of silicon nanowire photodetector, we construct a hexagonal silicon nanowire structure of photodetector. We cover the structure with zero-bandgap graphene and add Au grating at the same time, and finally use COMSOL software to model and analyze the structure. It is shown that in the optical band range between 0.5 μm and 1.5 μm, the graphene coverage and the Au grating can effectively enhance the light absorption performance of the device. What is more, the thickness of both graphene and Au grating has an effect on the performance of the device.
Laser & Optoelectronics Progress
- Publication Date: Mar. 10, 2024
- Vol. 61, Issue 5, 0504001 (2024)
Study on the Performance of Graphene/GaN Ultraviolet Photodetectors Regulated Through Interface Engineering (Invited)
Fangliang Gao, Kun Chen, Qing Liu, Xingfu Wang, Jirui Yang, Mingjun Xu, Yuhao He, Yuhao Shi, Tengwen Xu, Zhichao Yang, and Shuti Li
Interface engineering stands out as an effective method for enhancing the performance of photodetectors. This study presents ultraviolet(UV) photodetectors featuring a Gr (2D) /GaN (3D) van der Waals heterojunction, skillfully regulated through interface engineering control. The GaN film efficiently absorbs photons, generating electron-hole pairs promptly separated by the built-in electric field. Photogenerated holes traverse to the Gr side through the tunneling effect, while photogenerated electrons move towards the GaN side. At elevated built-in field levels, high-speed photogenerated carriers undergo impact ionization, leading to a multiplication of the photocurrent. The outcomes highlight the significant influence of lead sulfide quantum dots (PbS QDs) on the light absorption efficiency and photoelectric conversion efficiency of the device. Consequently, the device achieves a remarkable responsivity value of 395.2 A/W and a substantial detectivity value of 4.425×1015 Jones under 5 μW/cm2 light at -2 V. This research contributes to the application of interface engineering technology in Gr-based UV photodetectors, opening possibilities for the preparation of high-performance UV detectors. Interface engineering stands out as an effective method for enhancing the performance of photodetectors. This study presents ultraviolet(UV) photodetectors featuring a Gr (2D) /GaN (3D) van der Waals heterojunction, skillfully regulated through interface engineering control. The GaN film efficiently absorbs photons, generating electron-hole pairs promptly separated by the built-in electric field. Photogenerated holes traverse to the Gr side through the tunneling effect, while photogenerated electrons move towards the GaN side. At elevated built-in field levels, high-speed photogenerated carriers undergo impact ionization, leading to a multiplication of the photocurrent. The outcomes highlight the significant influence of lead sulfide quantum dots (PbS QDs) on the light absorption efficiency and photoelectric conversion efficiency of the device. Consequently, the device achieves a remarkable responsivity value of 395.2 A/W and a substantial detectivity value of 4.425×1015 Jones under 5 μW/cm2 light at -2 V. This research contributes to the application of interface engineering technology in Gr-based UV photodetectors, opening possibilities for the preparation of high-performance UV detectors.
Laser & Optoelectronics Progress
- Publication Date: Feb. 10, 2024
- Vol. 61, Issue 3, 0304001 (2024)
Superconducting Single-Photon Detector and Its Applications in Biology (Invited)
Lü Chaolin, Lixing You, Jian Qin, Guangzhao Xu, Yanyang Jiang, and Jinghao Shi
Since its invention in 2001, superconducting nanowire single-photon detector (SNSPD) has rapidly grown into a star photon detector in the near-infrared band. Up to date, its system detection efficiency has exceeded 95% at the wavelength of 1550 nm, dark count rate less than 1 cps (counts per second), timing jitter better than 10 ps, detection rate higher than 1 GHz, and it is widely used in the field of quantum information. Recently, limited by the low signal-to-noise ratio and afterpulsing of semiconductor single-photon detectors in the near-infrared band, researchers began to introduce SNSPDs into biology. This article introduces the detection principle and performance of SNSPD, and review the application status and development prospects of SNSPD in the field of biology. Since its invention in 2001, superconducting nanowire single-photon detector (SNSPD) has rapidly grown into a star photon detector in the near-infrared band. Up to date, its system detection efficiency has exceeded 95% at the wavelength of 1550 nm, dark count rate less than 1 cps (counts per second), timing jitter better than 10 ps, detection rate higher than 1 GHz, and it is widely used in the field of quantum information. Recently, limited by the low signal-to-noise ratio and afterpulsing of semiconductor single-photon detectors in the near-infrared band, researchers began to introduce SNSPDs into biology. This article introduces the detection principle and performance of SNSPD, and review the application status and development prospects of SNSPD in the field of biology.
Laser & Optoelectronics Progress
- Publication Date: Jan. 10, 2024
- Vol. 61, Issue 1, 0104002 (2024)
Research Progress of Multi-Band Compatible Infrared Camouflage Technology (Invited)
Qiang Li, Bing Qin, and Min Qiu
Infrared camouflage refers to the capability of hiding or changing the infrared radiation characteristics, hence improving the survival rate of the objects. However, advanced multi-band detection technologies have emerged as a significant threat to the objects, necessitating the development of multi-band compatible infrared camouflage technologies. To address the challenge, it's of vital importance to clarify the camouflage requirements of different bands and design hierarchical structures based on the difference in electromagnetic response and structure size in these bands. Finally, it's essential to recognize the shortcomings of existing research and promote camouflage technologies more applicable, easy to prepare, and lower cost. Infrared camouflage refers to the capability of hiding or changing the infrared radiation characteristics, hence improving the survival rate of the objects. However, advanced multi-band detection technologies have emerged as a significant threat to the objects, necessitating the development of multi-band compatible infrared camouflage technologies. To address the challenge, it's of vital importance to clarify the camouflage requirements of different bands and design hierarchical structures based on the difference in electromagnetic response and structure size in these bands. Finally, it's essential to recognize the shortcomings of existing research and promote camouflage technologies more applicable, easy to prepare, and lower cost.
Laser & Optoelectronics Progress
- Publication Date: Jan. 10, 2024
- Vol. 61, Issue 1, 0104001 (2024)
Low-Light Image Object Detection Based on Improved YOLOv5 Algorithm
Ziting Shu, Zebin Zhang, Yaozhe Song, Mengmeng Wu, and Xiaobing Yuan
Aiming at the low detection accuracy of existing object detection algorithms in a low-light environment, a dual-channel low-light image object detection algorithm called YOLOv5_DC according to an enhanced YOLOv5 algorithm is suggested. First, we synthesize low-light images using Gamma transformation and superimposing Gaussian noise to expand the dataset and promote the network's generalization. Second, a feature enhancement module is proposed. The channel attention method is used to integrate the low-level characteristics of the improved image and the original image to decrease the effect of noisy features and increase the network's feature extraction capabilities. Finally, a feature location module is added to the neck network to boost the response value of the feature map in the target area, allowing the network to focus more on the target area and improve the network detection capabilities. The experimental results show that the proposed YOLOv5_DC algorithm achieves higher detection accuracy. On the low-light object detection dataset known as ExDark*, the mean average precision (mAP) @0.5 of the proposed algorithm reaches 71.85%, which is 1.28 percentage points higher than the original YOLOv5 algorithm. Aiming at the low detection accuracy of existing object detection algorithms in a low-light environment, a dual-channel low-light image object detection algorithm called YOLOv5_DC according to an enhanced YOLOv5 algorithm is suggested. First, we synthesize low-light images using Gamma transformation and superimposing Gaussian noise to expand the dataset and promote the network's generalization. Second, a feature enhancement module is proposed. The channel attention method is used to integrate the low-level characteristics of the improved image and the original image to decrease the effect of noisy features and increase the network's feature extraction capabilities. Finally, a feature location module is added to the neck network to boost the response value of the feature map in the target area, allowing the network to focus more on the target area and improve the network detection capabilities. The experimental results show that the proposed YOLOv5_DC algorithm achieves higher detection accuracy. On the low-light object detection dataset known as ExDark*, the mean average precision (mAP) @0.5 of the proposed algorithm reaches 71.85%, which is 1.28 percentage points higher than the original YOLOv5 algorithm.
Laser & Optoelectronics Progress
- Publication Date: Feb. 25, 2023
- Vol. 60, Issue 4, 0404001 (2023)
Forward Current Transport in P-I-N Type GaN Ultraviolet Detector
Jinxiao Li, Zhen Liu, Sican Ye, Ao Lu, Wenyuan Hua, Ning Dang, and Dawei Yan
In this study, we demonstrate the preparation of P-I-N type GaN ultraviolet (UV) detectors on self-supported substrates, and then investigate their forward current transport mechanisms. The results show that the electron diffusion current starts to dominate only when the forward voltage VF>2 V. Moreover, the effective forbidden bandwidth Eg~2.21 eV is much lower than the ideal value, which can be attributed to the energy band perturbation introduced by the conductive dislocations. An ideal factor n>2 when 1.35 V<VF<2 V indicates that the electron defect-assisted tunneling current is the dominant current component. The current has a negative temperature coefficient, which is primarily caused by the increase in the effective forbidden bandwidth of the electron once it is excited to a higher energy conduction band. In the VF<0.8 V and 0.8 V<VF<1.35 V regions, the current-voltage curves are power dependent; this behavior is consistent with the electron space charge confinement mechanism. The power factors are eight and four, respectively, and two different effective energy bandwidths, corresponding to two exponentially decaying defect state distributions, are obtained from the characteristic temperature. In this study, we demonstrate the preparation of P-I-N type GaN ultraviolet (UV) detectors on self-supported substrates, and then investigate their forward current transport mechanisms. The results show that the electron diffusion current starts to dominate only when the forward voltage VF>2 V. Moreover, the effective forbidden bandwidth Eg~2.21 eV is much lower than the ideal value, which can be attributed to the energy band perturbation introduced by the conductive dislocations. An ideal factor n>2 when 1.35 V<VF<2 V indicates that the electron defect-assisted tunneling current is the dominant current component. The current has a negative temperature coefficient, which is primarily caused by the increase in the effective forbidden bandwidth of the electron once it is excited to a higher energy conduction band. In the VF<0.8 V and 0.8 V<VF<1.35 V regions, the current-voltage curves are power dependent; this behavior is consistent with the electron space charge confinement mechanism. The power factors are eight and four, respectively, and two different effective energy bandwidths, corresponding to two exponentially decaying defect state distributions, are obtained from the characteristic temperature.
Laser & Optoelectronics Progress
- Publication Date: Dec. 10, 2023
- Vol. 60, Issue 23, 2304002 (2023)
Effect of Germanium Dead Layer on Detection Efficiency of High-Purity Germanium Based on Monte Carlo Simulations
Haisheng Song, Rongni Pang, and Xiao Cai
In order to analyze and measure the radioactive content of samples more accurately and conveniently, a Monte Carlo application software tool (Geant4) is used to obtain the full energy peak efficiency curve of high-purity germanium (HPGe) detectors and thus to simulate and correct it in the measurement of radioactive samples. In particular, the different characteristic energies of a detector are measured in response to a point source 25 cm away from the HPGe probe. The experimental detection efficiency of γ-rays is compared with the simulation detection efficiency, and the influence of the dead layer on the detector efficiency of the HPGe crystal surface is studied by means of Geant4 simulations. The detection efficiency of the model is corrected by modifying the thickness of the upper and lower dead layers in turn, and the parameters of the Monte Carlo geometric model of the detector are optimized. Thereafter, the simulated efficiency of the optimized model is again compared with the measured efficiency of the point source, and the full energy peak efficiency curve of the HPGe detector in the range of 59.54‒1406 keV is obtained. The experimental measurement results show good agreement with the Monte Carlo simulations, exhibiting a relative error within 5%. The experimental results also demonstrate that the thickness of the dead layer on the surface of the HPGe crystal changes with the aging of the detector. After 7 years, the thickness of the dead layer increases from 0.5 mm to approximately 140 mm±0.05 mm. In order to analyze and measure the radioactive content of samples more accurately and conveniently, a Monte Carlo application software tool (Geant4) is used to obtain the full energy peak efficiency curve of high-purity germanium (HPGe) detectors and thus to simulate and correct it in the measurement of radioactive samples. In particular, the different characteristic energies of a detector are measured in response to a point source 25 cm away from the HPGe probe. The experimental detection efficiency of γ-rays is compared with the simulation detection efficiency, and the influence of the dead layer on the detector efficiency of the HPGe crystal surface is studied by means of Geant4 simulations. The detection efficiency of the model is corrected by modifying the thickness of the upper and lower dead layers in turn, and the parameters of the Monte Carlo geometric model of the detector are optimized. Thereafter, the simulated efficiency of the optimized model is again compared with the measured efficiency of the point source, and the full energy peak efficiency curve of the HPGe detector in the range of 59.54‒1406 keV is obtained. The experimental measurement results show good agreement with the Monte Carlo simulations, exhibiting a relative error within 5%. The experimental results also demonstrate that the thickness of the dead layer on the surface of the HPGe crystal changes with the aging of the detector. After 7 years, the thickness of the dead layer increases from 0.5 mm to approximately 140 mm±0.05 mm.
Laser & Optoelectronics Progress
- Publication Date: Dec. 10, 2023
- Vol. 60, Issue 23, 2304001 (2023)
High-Resolution Intelligent Imaging System with Wide Field of View Based on Eagle Eye
Peng Liu, Hongjie Ding, and Wang Zhang
Because of its special visual mechanism, eagle eye has several advantages, such as a wide field of view, remote detection, and high-resolution imaging. In this paper, based on the eagle-eye vision, an innovative and intelligent detection method is presented that can automatically search for specific targets in key areas and create high-resolution images aimed at being part of a missile-borne optical-electric detection platform. In the long-wave infrared spectrum, a high-resolution imaging system is designed with five apertures. Based on the Agent intelligent control theory, a multisensor collaborative control scheme is established to realize automatic target positioning in a wide field of view. The multi-aperture image mosaic and variable resolution image fusion methods are studied to achieve the overall acquisition of large field of view background and high-resolution target images. Results show that our multi-aperture detection system can effectively solve the contradiction between large field of view and high-resolution in the far-field detection under an optical dome environment. Because of its special visual mechanism, eagle eye has several advantages, such as a wide field of view, remote detection, and high-resolution imaging. In this paper, based on the eagle-eye vision, an innovative and intelligent detection method is presented that can automatically search for specific targets in key areas and create high-resolution images aimed at being part of a missile-borne optical-electric detection platform. In the long-wave infrared spectrum, a high-resolution imaging system is designed with five apertures. Based on the Agent intelligent control theory, a multisensor collaborative control scheme is established to realize automatic target positioning in a wide field of view. The multi-aperture image mosaic and variable resolution image fusion methods are studied to achieve the overall acquisition of large field of view background and high-resolution target images. Results show that our multi-aperture detection system can effectively solve the contradiction between large field of view and high-resolution in the far-field detection under an optical dome environment.
Laser & Optoelectronics Progress
- Publication Date: Feb. 20, 2022
- Vol. 59, Issue 4, 0404001 (2022)
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