High-speed solar-blind short wavelength ultraviolet radiation detectors based onκ(ε)-Ga_(2)O_(3)layers with Pt contacts were demonstrated and their properties were studied in detail.Theκ(ε)-Ga_(2)O_(3)layers were ...High-speed solar-blind short wavelength ultraviolet radiation detectors based onκ(ε)-Ga_(2)O_(3)layers with Pt contacts were demonstrated and their properties were studied in detail.Theκ(ε)-Ga_(2)O_(3)layers were deposited by the halide vapor phase epitaxy on patterned GaN templates with sapphire substrates.The spectral dependencies of the photoelectric properties of struc-tures were analyzed in the wavelength interval 200-370 nm.The maximum photo to dark current ratio,responsivity,detectiv-ity and external quantum efficiency of structures were determined as:180.86 arb.un.,3.57 A/W,1.78×10^(12) Hz^(0.5)∙cm·W^(-1) and 2193.6%,respectively,at a wavelength of 200 nm and an applied voltage of 1 V.The enhancement of the photoresponse was caused by the decrease in the Schottky barrier at the Pt/κ(ε)-Ga_(2)O_(3)interface under ultraviolet exposure.The detectors demon-strated could functionalize in self-powered mode due to built-in electric field at the Pt/κ(ε)-Ga_(2)O_(3)interface.The responsivity and external quantum efficiency of the structures at a wavelength of 254 nm and zero applied voltage were 0.9 mA/W and 0.46%,respectively.The rise and decay times in self-powered mode did not exceed 100 ms.展开更多
We study,by means of numerical simulation,the impact of doping and traps on the performance of the"solar blind"ultraviolet Schottky detector based on AlGaN.We implemented physical models and AlGaN material propertie...We study,by means of numerical simulation,the impact of doping and traps on the performance of the"solar blind"ultraviolet Schottky detector based on AlGaN.We implemented physical models and AlGaN material properties taken from the literature,or from the interpolation between the binary materials(GaN and AlN) weighted by the mole fractions.We found that doping and traps highly impact the spectral response of the device,and in particular a compromise in the doping concentration must be reached in order to optimize the spectral response of the detector.These results give us a powerful tool to quantitatively understand the impact of elaboration and processing conditions on photodetector characteristics,and thus identify the key issues for the development of the technology.展开更多
Fabrication and characterization of metal-semiconductor-metal ultraviolet (MSM UV) photodetector based on ZnO ultra thin (nano scale) films with Pd Schottky contact are reported. The ZnO thin film was grown on gla...Fabrication and characterization of metal-semiconductor-metal ultraviolet (MSM UV) photodetector based on ZnO ultra thin (nano scale) films with Pd Schottky contact are reported. The ZnO thin film was grown on glass substrate by thermal oxidation of preeposited zinc films using vacuum deposition technique. With applied voltage in the range from -3V to 3V, the contrast ratio, responsivity, and detectivity for an incident radiation of 0.1 mW at 365 nm wavelength were estimated. The proposed device exhibited a high gain which was attributed to the hole trapping at semiconductor-metal interface. I-V characteristics were studied and the parameters, such as ideality factor, leakage current, resistance-areaproduct, and barrier height, were extracted from the measured data.展开更多
This study describes the fabrication of ZnO-nanowire films by electro-chemical anodization of Zn foil. The ZnO films are characterized by field emission scanning electron microscopy, X-ray diffraction patterns, and tr...This study describes the fabrication of ZnO-nanowire films by electro-chemical anodization of Zn foil. The ZnO films are characterized by field emission scanning electron microscopy, X-ray diffraction patterns, and transmission electron microscopy, respectively. The ultraviolet (UV) photo-response properties of the surface-contacted ZnO film are studied through the current evolution processes under different relative humidities. Unlike the usually observed current spectra of the ZnO films, the drop time is shorter than the rise time. The photo-conductivity gain G and the response time T are both increased with the increase of the applied bias. The photo-conductivity gain G is lowered with the increase of the environmental humidity, while the response time τ- is increased. These results can be explained by considering three different surface processes: 1) the electron-hole (e-p) pair generation by the UV light illumination, 2) the following surface O2 species desorption, and 3) the photo-catalytic hydrolysis of water molecules adsorbed on the ZnO surface. The slow-rise and fast-drop current feature is suggested to originate from the sponge-like structure of the ZnO nanowires.展开更多
The high-temperature performance of 4H-SiC ultraviolet avalanche photodiodes(APDs)in both linear and Geiger modes is extensively investigated.During the temperature-dependent measurements,a fixed bias voltage is adopt...The high-temperature performance of 4H-SiC ultraviolet avalanche photodiodes(APDs)in both linear and Geiger modes is extensively investigated.During the temperature-dependent measurements,a fixed bias voltage is adopted for the device samples,which is much more practical and important for high-temperature applications.The results show that the fabricated 4H-SiC APDs are very stable and reliable at high temperatures.As the temperature increases from room temperature to 425 K,the dark current at 95%of the breakdown voltage increases slightly and remains lower than40 pA.In Geiger mode,our 4H-SiC APDs can be self-quenched in a passive-quenching circuit,which is expected for highspeed detection systems.Moreover,an interesting phenomenon is observed for the first time:the single-photon detection efficiency shows a non-monotonic variation as a function of temperature.The physical mechanism of the variation in hightemperature performance is further analyzed.The results in this work can provide a fundamental reference for researchers in the field of 4H-SiC APD ultraviolet detectors.展开更多
Detection of solar-blind ultraviolet(SB-UV)light is important in applications like confidential communication,flame detection,and missile warning system.However,the existing SB-UV photodetectors still show low sensiti...Detection of solar-blind ultraviolet(SB-UV)light is important in applications like confidential communication,flame detection,and missile warning system.However,the existing SB-UV photodetectors still show low sensitivities.In this work,we demonstrate the extraordinary SB-UV detection performance of α-In_(2)Se_(3 )phototransistors.Benefiting from the coupled semiconductor and ferroelectricity property,the phototransistor has an ultraweak detectable power of 17.85 fW,an ultrahigh gain of 1.2×10^(6),a responsivity of 2.6×10^(5) A/W,a detectivity of 1.3×10^(16) Jones and an ultralow noise-equivalent-power of 4.2×10^(–20 )W/Hz1/2 for 275 nm light.Its performance exceeds most other UV detectors,even including commercial photomultiplier tubes and avalanche photodiodes.It can be also implemented as an optoelectronic synapse for neuromorphic computing.A 784×300×10 artificial neural network(ANN)based on this optoelectronic synapse is constructed and demonstrated with a high recognition accuracy and good noise-tolerance for the Fashion-MNIST dataset.These extraordinary features endow this phototransistor with the potential for constructing advanced SB-UV detectors and intelligent hardware.展开更多
Based on the principles of metal-semiconductor-metal Schottky barrier photodetectors(MSM-PD), using the carrier rate equations,the circuit simulation model of a GaN-based MSM photovoltaic ultraviolet detector is con...Based on the principles of metal-semiconductor-metal Schottky barrier photodetectors(MSM-PD), using the carrier rate equations,the circuit simulation model of a GaN-based MSM photovoltaic ultraviolet detector is constructed through an appropriately equivalent process.By using the Pspice analytical function of Cadence soft on the model,the relationship between the photocurrent and the terminal voltage under different UV light powers is analyzed.The result shows that under the given UV power,the photocurrent increases and tends to become saturated gradually as the terminal voltage of the device increases,and that under different UV powers,the photocurrent increases with increasing incident power.Then the analysis of the relationship between the photocurrent and the terminal voltage under the different ratios of interdigital electrode space and width is carried out when the UV power is given.The results show that when the ratio of interdigital electrode space and width(L/W) equals 1,the photocurrent tends to be at a maximum.展开更多
基金Research of the photoelectric properties of theκ(ε)-Ga_(2)O_(3)films was supported by the Russian Science Foundation,grant number 20-79-10043-P.Fabrication of the ultraviolet detectors based on theκ(ε)-Ga_(2)O_(3)layers was supported by the grant under the Decree of the Government of the Rus-sian Federation No.220 of 09 April 2010(Agreement No.075-15-2022-1132 of 01 July 2022)Research of the structural prop-erties of theκ(ε)-Ga_(2)O_(3)was supported by the St.Petersburg State University,grant number 94034685.
文摘High-speed solar-blind short wavelength ultraviolet radiation detectors based onκ(ε)-Ga_(2)O_(3)layers with Pt contacts were demonstrated and their properties were studied in detail.Theκ(ε)-Ga_(2)O_(3)layers were deposited by the halide vapor phase epitaxy on patterned GaN templates with sapphire substrates.The spectral dependencies of the photoelectric properties of struc-tures were analyzed in the wavelength interval 200-370 nm.The maximum photo to dark current ratio,responsivity,detectiv-ity and external quantum efficiency of structures were determined as:180.86 arb.un.,3.57 A/W,1.78×10^(12) Hz^(0.5)∙cm·W^(-1) and 2193.6%,respectively,at a wavelength of 200 nm and an applied voltage of 1 V.The enhancement of the photoresponse was caused by the decrease in the Schottky barrier at the Pt/κ(ε)-Ga_(2)O_(3)interface under ultraviolet exposure.The detectors demon-strated could functionalize in self-powered mode due to built-in electric field at the Pt/κ(ε)-Ga_(2)O_(3)interface.The responsivity and external quantum efficiency of the structures at a wavelength of 254 nm and zero applied voltage were 0.9 mA/W and 0.46%,respectively.The rise and decay times in self-powered mode did not exceed 100 ms.
文摘We study,by means of numerical simulation,the impact of doping and traps on the performance of the"solar blind"ultraviolet Schottky detector based on AlGaN.We implemented physical models and AlGaN material properties taken from the literature,or from the interpolation between the binary materials(GaN and AlN) weighted by the mole fractions.We found that doping and traps highly impact the spectral response of the device,and in particular a compromise in the doping concentration must be reached in order to optimize the spectral response of the detector.These results give us a powerful tool to quantitatively understand the impact of elaboration and processing conditions on photodetector characteristics,and thus identify the key issues for the development of the technology.
基金support by Indo-Iraq Cultural Exchange Program of ICCR (Indian Council for Cultural Relations)
文摘Fabrication and characterization of metal-semiconductor-metal ultraviolet (MSM UV) photodetector based on ZnO ultra thin (nano scale) films with Pd Schottky contact are reported. The ZnO thin film was grown on glass substrate by thermal oxidation of preeposited zinc films using vacuum deposition technique. With applied voltage in the range from -3V to 3V, the contrast ratio, responsivity, and detectivity for an incident radiation of 0.1 mW at 365 nm wavelength were estimated. The proposed device exhibited a high gain which was attributed to the hole trapping at semiconductor-metal interface. I-V characteristics were studied and the parameters, such as ideality factor, leakage current, resistance-areaproduct, and barrier height, were extracted from the measured data.
基金Project supported by the National Natural Science Foundation of China (Grant No. 60907023)the Shandong Excellent Young Scientist Research Award Fund Project,China (Grant No. BS2011CL002)+1 种基金the Natural Science Foundation of Heilongjiang Province,China (Grant No. A200912)the Science and Technology Progress Project of Weihai,China (Grant Nos. IMJQ01110003 and 20090393)
文摘This study describes the fabrication of ZnO-nanowire films by electro-chemical anodization of Zn foil. The ZnO films are characterized by field emission scanning electron microscopy, X-ray diffraction patterns, and transmission electron microscopy, respectively. The ultraviolet (UV) photo-response properties of the surface-contacted ZnO film are studied through the current evolution processes under different relative humidities. Unlike the usually observed current spectra of the ZnO films, the drop time is shorter than the rise time. The photo-conductivity gain G and the response time T are both increased with the increase of the applied bias. The photo-conductivity gain G is lowered with the increase of the environmental humidity, while the response time τ- is increased. These results can be explained by considering three different surface processes: 1) the electron-hole (e-p) pair generation by the UV light illumination, 2) the following surface O2 species desorption, and 3) the photo-catalytic hydrolysis of water molecules adsorbed on the ZnO surface. The slow-rise and fast-drop current feature is suggested to originate from the sponge-like structure of the ZnO nanowires.
基金the National Natural Science Foundation of China(Grant No.61974134)Hebei Province Outstanding Youth Fund(Grant No.F2021516001).
文摘The high-temperature performance of 4H-SiC ultraviolet avalanche photodiodes(APDs)in both linear and Geiger modes is extensively investigated.During the temperature-dependent measurements,a fixed bias voltage is adopted for the device samples,which is much more practical and important for high-temperature applications.The results show that the fabricated 4H-SiC APDs are very stable and reliable at high temperatures.As the temperature increases from room temperature to 425 K,the dark current at 95%of the breakdown voltage increases slightly and remains lower than40 pA.In Geiger mode,our 4H-SiC APDs can be self-quenched in a passive-quenching circuit,which is expected for highspeed detection systems.Moreover,an interesting phenomenon is observed for the first time:the single-photon detection efficiency shows a non-monotonic variation as a function of temperature.The physical mechanism of the variation in hightemperature performance is further analyzed.The results in this work can provide a fundamental reference for researchers in the field of 4H-SiC APD ultraviolet detectors.
基金supported by the National Key R&D Program of China(Grant Nos.2021YFA1201500 and 2018YFA0703700)the National Natural Science Foundation of China(Nos.91964203,61974036,62274046,22179029,and 12204122)+2 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(Nos.XDB44000000)the Fundamental Research Funds for the Central Universities(No.2042021kf0067)CAS Key Laboratory of Nanosystem and Hierarchical Fabrication.The authors also gratefully acknowledge the support of Youth Innovation Promotion Association CAS.
文摘Detection of solar-blind ultraviolet(SB-UV)light is important in applications like confidential communication,flame detection,and missile warning system.However,the existing SB-UV photodetectors still show low sensitivities.In this work,we demonstrate the extraordinary SB-UV detection performance of α-In_(2)Se_(3 )phototransistors.Benefiting from the coupled semiconductor and ferroelectricity property,the phototransistor has an ultraweak detectable power of 17.85 fW,an ultrahigh gain of 1.2×10^(6),a responsivity of 2.6×10^(5) A/W,a detectivity of 1.3×10^(16) Jones and an ultralow noise-equivalent-power of 4.2×10^(–20 )W/Hz1/2 for 275 nm light.Its performance exceeds most other UV detectors,even including commercial photomultiplier tubes and avalanche photodiodes.It can be also implemented as an optoelectronic synapse for neuromorphic computing.A 784×300×10 artificial neural network(ANN)based on this optoelectronic synapse is constructed and demonstrated with a high recognition accuracy and good noise-tolerance for the Fashion-MNIST dataset.These extraordinary features endow this phototransistor with the potential for constructing advanced SB-UV detectors and intelligent hardware.
基金Project supported by the National Natural Science Foundation of China(Nos.60976011,51072196,51072195)the National Basic Research Program of China(No.2011CB301901)
文摘Based on the principles of metal-semiconductor-metal Schottky barrier photodetectors(MSM-PD), using the carrier rate equations,the circuit simulation model of a GaN-based MSM photovoltaic ultraviolet detector is constructed through an appropriately equivalent process.By using the Pspice analytical function of Cadence soft on the model,the relationship between the photocurrent and the terminal voltage under different UV light powers is analyzed.The result shows that under the given UV power,the photocurrent increases and tends to become saturated gradually as the terminal voltage of the device increases,and that under different UV powers,the photocurrent increases with increasing incident power.Then the analysis of the relationship between the photocurrent and the terminal voltage under the different ratios of interdigital electrode space and width is carried out when the UV power is given.The results show that when the ratio of interdigital electrode space and width(L/W) equals 1,the photocurrent tends to be at a maximum.