Liquid-phase exfoliation was employed to synthesize Sr_(2)Nb_(3)O_(10) perovskite nanosheets with thicknesses down to 1.76 nm.Transmission electron microscopy(TEM),atomic force microscope(AFM),X-ray photoelectron spec...Liquid-phase exfoliation was employed to synthesize Sr_(2)Nb_(3)O_(10) perovskite nanosheets with thicknesses down to 1.76 nm.Transmission electron microscopy(TEM),atomic force microscope(AFM),X-ray photoelectron spectrometer(XPS),and other characterization techniques were used to evaluate the atomic structure and chemical composition of the exfoliated nanosheets.A UV photodetector based on individual Sr_(2)Nb_(3)O_(10) nanosheets was prepared to demonstrate the application of an ultraviolet(UV) photodetector.The UV photodetector exhibited outstanding photocurrent and responsivity with a responsivity of 3×10^(5) A·W^(-1) at 5 V bias under 280 nm illumination,a photocurrent of 60 nA,and an on/off ratio of 3×10^(2).展开更多
High response organic ultraviolet photodetectors（UV-PDs） were demonstrated with 4,4＇,4”- tris[3-methyl-pheny（phenyl）amino]triphenylamine（m-MTDATA） and two Re（Ⅰ） complexes, （bathocuproine）- Re（CO）3CI（Re...High response organic ultraviolet photodetectors（UV-PDs） were demonstrated with 4,4＇,4”- tris[3-methyl-pheny（phenyl）amino]triphenylamine（m-MTDATA） and two Re（Ⅰ） complexes, （bathocuproine）- Re（CO）3CI（Re-BCP） and （bathophenanthroline）Re（CO）3Cl（Re-Bphen） to act as the electron donor and acceptor, re- spectively. UV-PDs have the configuration of indium tin oxide（ITO）/m-MTDATA（25 nm）/m-MTDATA：Re-complex （25-35 nm）/Re-complex（20 nm）/LiF（l nm）/Al（200 nm） with different blend layer thicknesses of 25, 30 and 35 nm. The optimized PD based on Re-Bphen offers a corrected-dark photocurrent up to 760μA/cm^2 at -10 V, corresponding to a response of 310 mA/W which is among the best values reported for organic UV-PDs. Excellent electron transport ability makes for such high photo-to-electron conversion.展开更多
A self-powered graphene-based photodetector with high performance is particularly useful for device miniaturization and to save energy.Here,we report a graphene/silicon carbide（SiC）-based self-powered ultraviolet ph...A self-powered graphene-based photodetector with high performance is particularly useful for device miniaturization and to save energy.Here,we report a graphene/silicon carbide（SiC）-based self-powered ultraviolet photodetector that exhibits a current responsivity of 7.4 m A/W with a response frequency of over a megahertz under 325-nm laser irradiation.The built-in photovoltage of the photodetector is about four orders of magnitude higher than previously reported results for similar devices.These favorable properties are ascribed to the ingenious device design using the combined advantages of graphene and SiC,two terminal electrodes,and asymmetric light irradiation on one of the electrodes.Importantly,the photon energy is larger than the band gap of SiC.This self-powered photodetector is compatible with modern semiconductor technology and shows potential for applications in ultraviolet imaging and graphene-based integrated circuits.展开更多
Due to the wide application of UV-A(320 nm–400 nm)and UV-C(200 nm–280 nm)photodetectors,dual-wavelength(UV-A/UV-C)photodetectors are promising for future markets.A dual-wavelength UV photodetector based on vertical(...Due to the wide application of UV-A(320 nm–400 nm)and UV-C(200 nm–280 nm)photodetectors,dual-wavelength(UV-A/UV-C)photodetectors are promising for future markets.A dual-wavelength UV photodetector based on vertical(Al,Ga)N nanowires and graphene has been demonstrated successfully,in which graphene is used as a transparent electrode.Both UV-A and UV-C responses can be clearly detected by the device,and the rejection ratio(R254 nm/R450 nm)exceeds35 times at an applied bias of-2 V.The short response time of the device is less than 20 ms.Furthermore,the underlying mechanism of double ultraviolet responses has also been analyzed systematically.The dual-wavelength detections could mainly result from the appropriate ratio of the thicknesses and the enough energy band difference of(Al,Ga)N and Ga N sections.展开更多
An AIGaN-based back-illuminated ultraviolet p-i-n detector is designed and its performance is analysed both simulately and experimentally. The width of p- and i-regions has been optimized to the best theoretic values....An AIGaN-based back-illuminated ultraviolet p-i-n detector is designed and its performance is analysed both simulately and experimentally. The width of p- and i-regions has been optimized to the best theoretic values. It is indicated that the changing of responsivity with increase of bias can not be attributed to the expansion of depletion layer as it is believed, but to two reasons： 1） the effect of GaN/AlGaN heterojunction barrier to block the electrons decreases with higher bias and 2） the recombination rate of excess carriers decreases due to the building up of an electric field in depletion region. At zero bias, the simulated responsivity reaches its maximum of 0.12 A/W with quantum efficiency of 55.1%. The measured peak responsivity is more than 0.09 A/W with quantum efficiency greater than 41.6%. The experimental data are almost consistent with the results of the simulation.展开更多
In this paper, we report a Schottky ultraviolet photodetector based on poly（3,4-ethylenedioxy-thiophene）poly（styrenesulfonate）（PEDOT：PSS） transparent electrode contacts to Mg0.1Zn0.9O. The I-V characteristic cu...In this paper, we report a Schottky ultraviolet photodetector based on poly（3,4-ethylenedioxy-thiophene）poly（styrenesulfonate）（PEDOT：PSS） transparent electrode contacts to Mg0.1Zn0.9O. The I-V characteristic curves of the device are measured in the dark condition and under the illumination of a 340-nm UV light. The device shows a typical rectifying behavior with a current rectification ratio of 103 at ±2 V, which exhibits a good Schottky behavior. The phototo-dark current ratio is high, which is 1×103at-4 V. A peak response of 0.156 A/W at 340 nm is observed. The device also exhibits a wide response from 250 nm to 340 nm, with a response larger than 0.1 A/W. It covers the UV-B region（280 nm-320 nm）, which makes the device very suitable for the detection of UV-B light.展开更多
A novel integrated ultraviolet（UV） photodetector has been proposed, which realizes a high UV selectivity by combining a conventional UV-selective photodiode with an extra infrared（IR） photodiode. The IR photodiode...A novel integrated ultraviolet（UV） photodetector has been proposed, which realizes a high UV selectivity by combining a conventional UV-selective photodiode with an extra infrared（IR） photodiode. The IR photodiode is designed for compensating the photocurrent response of the UV photodiode in the infrared band and is 15 times smaller than the UV one. The integrated photodetector has been fabricated in a 0.35 μm standard CMOS technology. Some critical performance indices of this new structure photodetector, such as spectral responsivity, breakdown voltage, quenching waveform, and transient response, are measured and analyzed. Test results show that the complementary UV–IR photodetector has a maximum spectral responsivity of 0.27 A·W-1 at the wavelength of 400 nm. The device has a high UV selectivity of 3000,which is much higher than that of the single UV photodiode.展开更多
The slower response speed is the main problem in the application of ZnO quantum dots(QDs)photodetector,which has been commonly attributed to the presence of excess oxygen vacancy defects and oxygen adsorption/desorpti...The slower response speed is the main problem in the application of ZnO quantum dots(QDs)photodetector,which has been commonly attributed to the presence of excess oxygen vacancy defects and oxygen adsorption/desorption processes.However,the detailed mechanism is still not very clear.Herein,the properties of ZnO QDs and their photodetectors with different amounts of oxygen vacancy(VO)defects controlled by hydrogen peroxide(H_(2)O_(2))solution treatment have been investigated.After H_(2)O_(2) solution treatment,VO concentration of ZnO QDs decreased.The H_(2)O_(2) solution-treated device has a higher photocurrent and a lower dark current.Meanwhile,with the increase in VO concentration of ZnO QDs,the response speed of the device has been improved due to the increase of oxygen adsorption/desorption rate.More interestingly,the response speed of the device became less sensitive to temperature and oxygen concentration with the increase of VO defects.The findings in this work clarify that the surface VO defects of ZnO QDs could enhance the photoresponse speed,which is helpful for sensor designing.展开更多
GaN has been widely used in the fabrication of ultraviolet photodetectors because of its outstanding properties.In this paper,we report a graphene–GaN nanorod heterostructure photodetector with fast photoresponse in ...GaN has been widely used in the fabrication of ultraviolet photodetectors because of its outstanding properties.In this paper,we report a graphene–GaN nanorod heterostructure photodetector with fast photoresponse in the UV range.GaN nanorods were fabricated by a combination mode of dry etching and wet etching.Furthermore,a graphene–GaN nanorod heterostructure ultraviolet detector was fabricated and its photoelectric properties were measured.The device exhibits a fast photoresponse in the UV range.The rising time and falling time of the transient response were 13 and 8 ms,respectively.A high photovoltaic responsivity up to 13.9 A/W and external quantum efficiency up to 479%were realized at the UV range.The specific detectivity D*=1.44×10^(10) Jones was obtained at–1 V bias in ambient conditions.The spectral response was measured and the highest response was observed at the 360 nm band.展开更多
We report fabrication and characterization of organic heterojunction UV detectors based on N,N＇-bis（naphthalen- 1-y1）-N,N＇-bis （phenyl） benzidine （NPB） and fullerene C60. The effects of different thicknesses o...We report fabrication and characterization of organic heterojunction UV detectors based on N,N＇-bis（naphthalen- 1-y1）-N,N＇-bis （phenyl） benzidine （NPB） and fullerene C60. The effects of different thicknesses of NPB and C60 layers are studied and compared. Notably, the optimal thicknesses of electron acceptor C60 and electron donor NPB are 40 nm and 80 nm, respectively. The J V characteristic curves of the device demonstrate a three-order- of-magnitude difference when illuminated under a 350nm UV light and in the dark at -0.5 V. The device exhibits high sensitivity in the region of 320-380nm with the peak located around 35Onm. Especially, it shows excellent photo-response characteristic with a responsivity as high as 315 mA/W under the illumination of 192μW.cm 2 350nm UV light at -5 V. These results indicate that the NPB/C60 heterojunction structure device might be used as low-cost low-voltage UV photodetectors.展开更多
Ultraviolet(UV) photodetectors(PDs) have drawn great attention in recent years due to their potential application in civil and military fields. Because of its ultrawide bandgap, low cost, strong radiation hardness, an...Ultraviolet(UV) photodetectors(PDs) have drawn great attention in recent years due to their potential application in civil and military fields. Because of its ultrawide bandgap, low cost, strong radiation hardness, and high thermal and chemical stability with high visible-light transparency, Ga_2O_3 is regarded as the most promising candidate for UV detection.Furthermore, the bandgap of Ga_2O_3 is as high as 4.7–4.9 eV, directly corresponding to the solar-blind UV detection band with wavelength less than 280 nm. There is no need of doping in Ga_2O_3 to tune its bandgap, compared to AlGaN, MgZnO,etc, thereby avoiding alloy composition fluctuations and phase separation. At present, solar-blind Ga_2O_3 photodetectors based on single crystal or amorphous Ga_2O_3 are mainly focused on metal–semiconductor–metal and Schottky photodiodes.In this work, the recent achievements of Ga_2O_3 photodetectors are systematically reviewed. The characteristics and performances of different photodetector structures based on single crystal Ga_2O_3 and amorphous Ga_2O_3 thin film are analyzed and compared. Finally, the prospects of Ga_2O_3 UV photodetectors are forecast.展开更多
Ultraviolet(UV) photodetectors have attracted more and more attention due to their great potential applications in missile tracking, flame detecting, pollution monitoring, ozone layer monitoring, and so on. Owing to t...Ultraviolet(UV) photodetectors have attracted more and more attention due to their great potential applications in missile tracking, flame detecting, pollution monitoring, ozone layer monitoring, and so on. Owing to the special characteristics of large bandgap, solution processable, low cost, environmentally friendly, etc., wide bandgap oxide semiconductor materials, such as ZnO, ZnMgO, Ga_2O_3, TiO_2, and Ni O, have gradually become a series of star materials in the field of semiconductor UV detection. In this paper, a review is presented on the development of UV photodetectors based on wide bandgap oxide semiconductor films.展开更多
We choose 8-hydroxyquinoline derivative-metal complexes（Beq,Mgq,and Znq） as the acceptors（A） and 4,4＇,4”-tri-（2-methylphenyl phenylamino） triphenylaine（m-MTDATA） as the donor（D） respectively to study the e...We choose 8-hydroxyquinoline derivative-metal complexes（Beq,Mgq,and Znq） as the acceptors（A） and 4,4＇,4”-tri-（2-methylphenyl phenylamino） triphenylaine（m-MTDATA） as the donor（D） respectively to study the existing energy transfer process in the organic ultraviolet（UV） photodetector（PD）,which has an important influence on the sensitivity of PDs.The energy transfer process from D to A without exciplex formation is discussed,differing from the working mechanism of previous PDs with Gaq[Zisheng Su,Wenlian Li,Bei Chu,Tianle Li,Jianzhuo Zhu,Guang Zhang,Fei Yan,Xiao Li,Yiren Chen and Chun-Sing Lee 2008 Appl.Phys.Lett.93 103309）]and REq[J.B.Wang,W.L.Li,B.Chu,L.L.Chen,G.Zhang,Z.S.Su,Y.R.Chen,D.F.Yang,J.Z.Zhu,S.H.Wu,F.Yan,H.H.Liu,C.S.Lee 2010 Org.Electron.111301]used as an A material.Under 365-nm UV irradiation with an intensity of 1.2 mW/cm^2,the m-MTDATA：Beq blend device with a weight ratio of 1：1 shows a response of 192 mAAV with a detectivity of 6.5 × 10^（11） Jones,which exceeds those of PDs based on Mgq（146 mA/W） and Znq（182 mA/W） due to better energy level alignment between m-MTDATA/Beq and lower radiative decay.More photophysics processes of the PDs involved are discussed in detail.展开更多
A self-powered ultraviolet photodetector(UV PD)with van der Waals(vdW)Schottky junction based on TiO_(2) nanorod arrays/Au-modulated V2 CTx MXene is reported.The Schottky junction enables the device to operate in self...A self-powered ultraviolet photodetector(UV PD)with van der Waals(vdW)Schottky junction based on TiO_(2) nanorod arrays/Au-modulated V2 CTx MXene is reported.The Schottky junction enables the device to operate in self-powered mode.The dangling bond-free surface of V2 CTx MXene reduces the charge recombination at the junction interface.Meanwhile,V2 CTx MXene,with the work function(WF)increasing to 5.35 eV,forms a hole transport layer by contacting with Au electrode,which facilitates the carrier extraction.The electron lifetime in the device has prolonged to 8.95μs.As a result,the responsivity and detectivity of the PD have achieved 28 mA/W and 1.2×10^(11) cm Hz1/2/W(340 nm,65 mW/cm2,0 V),respectively.In addition,the presence of the Au electrode prevents the vanadium from coming into contact with oxygen and oxidizing,preserving the properties of the V2 CTx films.After 180 days of exposure to the atmosphere,the device performance remained at a particularly high level,indicating enhanced durability.This work points out an effective approach to modulate the properties of V2 CTx to obtain the high performance and stability of the UV PD.展开更多
A two-dimensional model of a 4H-SiC metal-semiconductor-metal（MSM） ultraviolet photodetector has been established using a self-consistent numerical calculation method.The structure-dependent spectral response of a 4...A two-dimensional model of a 4H-SiC metal-semiconductor-metal（MSM） ultraviolet photodetector has been established using a self-consistent numerical calculation method.The structure-dependent spectral response of a 4H-SiC MSM detector is calculated by solving Poisson＇s equation,the current continuity equation and the current density equation.The calculated results are verified with experimental data.With consideration of the reflection and absorption on the metal contacts,a detailed study involving various electrode heights（H）,spacings （S） and widths（W） reveals conclusive results in device design.The mechanisms responsible for variations of responsivity with those parameters are analyzed.The findings show that responsivity is inversely proportional to electrode height and is enhanced with an increase of electrode spacing and width.In addition,the ultraviolet （UV）-to-visible rejection ratio is 103.By optimizing the device structure at 10 V bias,a responsivity as high as 180.056 mA/W,a comparable quantum efficiency of 77.93%and a maximum UV-to-visible rejection ratio of 1875 are achieved with a detector size of H = 50 nm,S =9μm and W = 3μm.展开更多
Ternary layered compound materials(bismuth oxyhalides and metal phosphorus trichalcogenides)stand out in electronic and optoelectronic fields due to their interesting physical properties.However,few studies focus on t...Ternary layered compound materials(bismuth oxyhalides and metal phosphorus trichalcogenides)stand out in electronic and optoelectronic fields due to their interesting physical properties.However,few studies focus on the preparation of high-quality two-dimensional(2D)BiOBr crystals with a typical layered structure,let alone their optoelectronic applications.Here,for the first time,high-quality 2D BiOBr crystals with ultrathin thicknesses(less than 10 nm)and large domain sizes(~100μm)were efficiently prepared via a modified space-confined chemical vapor deposition(SCCVD)method.It is demonstrated that a moderate amount of H2O molecules in the SCCVD system greatly promote the formation of high-quality 2D BiOBr crystals because of the strong polarity of H2O molecules.In addition,a linear relationship between the thickness of BiOBr nanosheets and Raman shift of A1g(1)mode was found.Corresponding theoretical calculations were carried out to verify the experimental data.Furthermore,the BiOBr-based photodetector was fabricated,exhibiting excellent performances with a responsivity of 12.4 A W-1 and a detectivity of 1.6×1013 Jones at 365 nm.This study paves the way for controllable preparation of high-quality 2D BiOBr crystals and implies intriguing opportunities of them in optoelectronic applications.展开更多
Based on thermionic emission theory,a model of a 6H-SiC metal-semiconductor-metal（MSM） ultraviolet photodetector is established with the simulation package ISE-TCAD.A device with 3μm electrode width（W） and 3μm e...Based on thermionic emission theory,a model of a 6H-SiC metal-semiconductor-metal（MSM） ultraviolet photodetector is established with the simulation package ISE-TCAD.A device with 3μm electrode width（W） and 3μm electrode spacing（L） is simulated.The findings show that the MSM photodetector has quite a low dark current of 15 pA at 10V bias and the photocurrent is two orders of magnitude higher than the dark current.The influences of different structures on dark and illuminated current-voltage characteristics of the MSM photodetector are investigated to optimize the device parameters.Simulation results indicate that the maximum photocurrent and the highest ratio of photocurrent to dark current at 15 V bias are 5.3 nA and 327 with device parameters of W=6μm,L=3μm and W =3μm,L=6μm,respectively.展开更多
Organic photochromic materials have drawn considerable attention for their potential applications in large-scale and low-cost optoelectronics owing to unique tunable physicochemical properties.For organic photodetecto...Organic photochromic materials have drawn considerable attention for their potential applications in large-scale and low-cost optoelectronics owing to unique tunable physicochemical properties.For organic photodetectors,photochromic materials have realized optical and electrical engineering of semiconductor layers,which incorporate not only tunable performance,but also functionalities to optoelectronic devices.However,the essential challenge is to assemble large-area photochromic micro-and nanostructure arrays with controllable geometry and precise alignment,which restricts the integration of multifunctional optoelectronic devices.Herein,we fabricate organic photochromic one-dimensional(1D)arrays via a feasible solution process through the confined crystallization of organic molecules.By modulating and controlling the photoisomerization behaviors,these 1D photochromic arrays possess broad spectral tunability,which ensure tunable photoresponse.Furthermore,we investigate the crystallographic transition and electronic performance variation of these 1D photochromic arrays.By adjusting the dwell time of ultraviolet(UV)irradiation,the UV photochromic photodetectors realize tunable and repeatable responsivity from 85.6 to 0.709 mA/W.Our work provides new possibilities for optical and electrical engineering of photochromic microwires towards the integration of multifunctional optoelectronic devices.展开更多
A novel semicircular electrode metal-semiconductor-metal（SEMSM） ultraviolet detector is modeled, investigated and characterized with a self-consistent numerical calculation method.For the purpose of model and perfor...A novel semicircular electrode metal-semiconductor-metal（SEMSM） ultraviolet detector is modeled, investigated and characterized with a self-consistent numerical calculation method.For the purpose of model and performance verification,a comprehensive comparison of the SEMSM detector and a conventional electrode MSM detector is carried out with experimental data.The results indicate that the physical models are able to predict the enhanced device features.Moreover,the structural parameters have been adjusted appropriately to optimize the SEMSM detector.The findings show that a device with a 2μm finger radius and 3 /mi spacing exhibits outstanding characteristics in terms of a peak responsivity of 0.177 A/W at 290 nm,a maximum external quantum efficiency of over 75%,and a comparable normalized photocurrent to dark current ratio of 1.192×10^（-1） W^（-1） at 0.3 V bias. These results demonstrate that the SEMSM detector has excellent performance for optoelectronic integrated circuit applications.展开更多
By utilizing Schottky contact in device fabrication,we have constructed fast response ultraviolet photodetectors based on the solution-processed Zn O nanocrystals.At 5 V,the detector exhibits fast photoresponse with a...By utilizing Schottky contact in device fabrication,we have constructed fast response ultraviolet photodetectors based on the solution-processed Zn O nanocrystals.At 5 V,the detector exhibits fast photoresponse with a rise time of 20 ns and fall time of 350 ns,which is one of the fastest response time among the reported Zn O-based photodetectors.The results reported in this paper may show great promise for fast response optoelectronic devices based on the solution-processed nanocrystals.展开更多
基金Funded by the National Natural Science Foundation of China(Nos.51872214 and 52172124)the Fundamental Research Funds for the Central Universities(WUT:2021Ⅲ019JC and 2018Ⅲ041GX)。
文摘Liquid-phase exfoliation was employed to synthesize Sr_(2)Nb_(3)O_(10) perovskite nanosheets with thicknesses down to 1.76 nm.Transmission electron microscopy(TEM),atomic force microscope(AFM),X-ray photoelectron spectrometer(XPS),and other characterization techniques were used to evaluate the atomic structure and chemical composition of the exfoliated nanosheets.A UV photodetector based on individual Sr_(2)Nb_(3)O_(10) nanosheets was prepared to demonstrate the application of an ultraviolet(UV) photodetector.The UV photodetector exhibited outstanding photocurrent and responsivity with a responsivity of 3×10^(5) A·W^(-1) at 5 V bias under 280 nm illumination,a photocurrent of 60 nA,and an on/off ratio of 3×10^(2).
基金Supported by the National Natural Science Foundation of China(No.60978059)the Program for New Century Excellent Talents in Universities of China(No.NCET-10-0176)+1 种基金the Key Project of Ministry of Education of China(No.210053)the Natural Science Foundation of Jilin Province,China(Nos.20101543 and 20100549)
文摘High response organic ultraviolet photodetectors（UV-PDs） were demonstrated with 4,4＇,4”- tris[3-methyl-pheny（phenyl）amino]triphenylamine（m-MTDATA） and two Re（Ⅰ） complexes, （bathocuproine）- Re（CO）3CI（Re-BCP） and （bathophenanthroline）Re（CO）3Cl（Re-Bphen） to act as the electron donor and acceptor, re- spectively. UV-PDs have the configuration of indium tin oxide（ITO）/m-MTDATA（25 nm）/m-MTDATA：Re-complex （25-35 nm）/Re-complex（20 nm）/LiF（l nm）/Al（200 nm） with different blend layer thicknesses of 25, 30 and 35 nm. The optimized PD based on Re-Bphen offers a corrected-dark photocurrent up to 760μA/cm^2 at -10 V, corresponding to a response of 310 mA/W which is among the best values reported for organic UV-PDs. Excellent electron transport ability makes for such high photo-to-electron conversion.
基金Project supported by the National Key Basic Research Program of China(Grant Nos.2011CB932700 and 2013CBA01603)the National Natural Science Foundation of China(Grant Nos.51472265 and 51272279)
文摘A self-powered graphene-based photodetector with high performance is particularly useful for device miniaturization and to save energy.Here,we report a graphene/silicon carbide（SiC）-based self-powered ultraviolet photodetector that exhibits a current responsivity of 7.4 m A/W with a response frequency of over a megahertz under 325-nm laser irradiation.The built-in photovoltage of the photodetector is about four orders of magnitude higher than previously reported results for similar devices.These favorable properties are ascribed to the ingenious device design using the combined advantages of graphene and SiC,two terminal electrodes,and asymmetric light irradiation on one of the electrodes.Importantly,the photon energy is larger than the band gap of SiC.This self-powered photodetector is compatible with modern semiconductor technology and shows potential for applications in ultraviolet imaging and graphene-based integrated circuits.
基金the National Key Research and Development Program of China(Grant No.2018YFB0406602)Natural Science Foundation of Jiangsu Province,China(Grant No.BK20180252)+6 种基金Key Research Program of Frontier Sciences,CAS(Grant No.ZDBS-LY-JSC034)the National Natural Science Foundation of China(Grant Nos.61804163,61875224,and 61827823)the Key Research and Development Program of Jiangsu Province,China(Grant No.BE2018005)Natural Science Foundation of Jiangxi Province,China(Grant No.20192BBEL50033)Research Program of Scientific Instrument,Equipment of CAS(Grant No.YJKYYQ20200073)SINANO(Grant Nos.Y8AAQ21001 and Y4JAQ21001)Vacuum Interconnected Nanotech Workstation(Grant Nos.Nano-X and B2006)。
文摘Due to the wide application of UV-A(320 nm–400 nm)and UV-C(200 nm–280 nm)photodetectors,dual-wavelength(UV-A/UV-C)photodetectors are promising for future markets.A dual-wavelength UV photodetector based on vertical(Al,Ga)N nanowires and graphene has been demonstrated successfully,in which graphene is used as a transparent electrode.Both UV-A and UV-C responses can be clearly detected by the device,and the rejection ratio(R254 nm/R450 nm)exceeds35 times at an applied bias of-2 V.The short response time of the device is less than 20 ms.Furthermore,the underlying mechanism of double ultraviolet responses has also been analyzed systematically.The dual-wavelength detections could mainly result from the appropriate ratio of the thicknesses and the enough energy band difference of(Al,Ga)N and Ga N sections.
文摘An AIGaN-based back-illuminated ultraviolet p-i-n detector is designed and its performance is analysed both simulately and experimentally. The width of p- and i-regions has been optimized to the best theoretic values. It is indicated that the changing of responsivity with increase of bias can not be attributed to the expansion of depletion layer as it is believed, but to two reasons： 1） the effect of GaN/AlGaN heterojunction barrier to block the electrons decreases with higher bias and 2） the recombination rate of excess carriers decreases due to the building up of an electric field in depletion region. At zero bias, the simulated responsivity reaches its maximum of 0.12 A/W with quantum efficiency of 55.1%. The measured peak responsivity is more than 0.09 A/W with quantum efficiency greater than 41.6%. The experimental data are almost consistent with the results of the simulation.
基金Project supported by the National Natural Science Foundation of China(Grant No.50972007)the National Basic Research Program of China(Grant No.2011CB932703)+1 种基金the National Natural Science Foundation for Distinguished Young Scholars of China(Grant No.60825407)the Opened Fund of the State Key Laboratory on Integrated Optoelectronics
文摘In this paper, we report a Schottky ultraviolet photodetector based on poly（3,4-ethylenedioxy-thiophene）poly（styrenesulfonate）（PEDOT：PSS） transparent electrode contacts to Mg0.1Zn0.9O. The I-V characteristic curves of the device are measured in the dark condition and under the illumination of a 340-nm UV light. The device shows a typical rectifying behavior with a current rectification ratio of 103 at ±2 V, which exhibits a good Schottky behavior. The phototo-dark current ratio is high, which is 1×103at-4 V. A peak response of 0.156 A/W at 340 nm is observed. The device also exhibits a wide response from 250 nm to 340 nm, with a response larger than 0.1 A/W. It covers the UV-B region（280 nm-320 nm）, which makes the device very suitable for the detection of UV-B light.
基金supported by the National Natural Science Foundation of China(Grant No.61274043)the Key Project of the Ministry of Education of China(Grant No.212125)the State Key Program of the National Natural Science Foundation of China(Grant No.61233010)
文摘A novel integrated ultraviolet（UV） photodetector has been proposed, which realizes a high UV selectivity by combining a conventional UV-selective photodiode with an extra infrared（IR） photodiode. The IR photodiode is designed for compensating the photocurrent response of the UV photodiode in the infrared band and is 15 times smaller than the UV one. The integrated photodetector has been fabricated in a 0.35 μm standard CMOS technology. Some critical performance indices of this new structure photodetector, such as spectral responsivity, breakdown voltage, quenching waveform, and transient response, are measured and analyzed. Test results show that the complementary UV–IR photodetector has a maximum spectral responsivity of 0.27 A·W-1 at the wavelength of 400 nm. The device has a high UV selectivity of 3000,which is much higher than that of the single UV photodiode.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.62074148,61875194,11727902,12074372,11774341,11974344,61975204,and 11804335)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Grant No.2020225)the Open Project of the State Key Laboratory of Luminescence and Applications(Grant Nos.SKLA-2020-02 and SKLA-2020-06).
文摘The slower response speed is the main problem in the application of ZnO quantum dots(QDs)photodetector,which has been commonly attributed to the presence of excess oxygen vacancy defects and oxygen adsorption/desorption processes.However,the detailed mechanism is still not very clear.Herein,the properties of ZnO QDs and their photodetectors with different amounts of oxygen vacancy(VO)defects controlled by hydrogen peroxide(H_(2)O_(2))solution treatment have been investigated.After H_(2)O_(2) solution treatment,VO concentration of ZnO QDs decreased.The H_(2)O_(2) solution-treated device has a higher photocurrent and a lower dark current.Meanwhile,with the increase in VO concentration of ZnO QDs,the response speed of the device has been improved due to the increase of oxygen adsorption/desorption rate.More interestingly,the response speed of the device became less sensitive to temperature and oxygen concentration with the increase of VO defects.The findings in this work clarify that the surface VO defects of ZnO QDs could enhance the photoresponse speed,which is helpful for sensor designing.
基金supported by the Science Foundation of Changchun University of Science and Technology under Grant No. 6141B010328
文摘GaN has been widely used in the fabrication of ultraviolet photodetectors because of its outstanding properties.In this paper,we report a graphene–GaN nanorod heterostructure photodetector with fast photoresponse in the UV range.GaN nanorods were fabricated by a combination mode of dry etching and wet etching.Furthermore,a graphene–GaN nanorod heterostructure ultraviolet detector was fabricated and its photoelectric properties were measured.The device exhibits a fast photoresponse in the UV range.The rising time and falling time of the transient response were 13 and 8 ms,respectively.A high photovoltaic responsivity up to 13.9 A/W and external quantum efficiency up to 479%were realized at the UV range.The specific detectivity D*=1.44×10^(10) Jones was obtained at–1 V bias in ambient conditions.The spectral response was measured and the highest response was observed at the 360 nm band.
基金Supported by the National Natural Science Foundation of China under Grant Nos 61274068 and 61404058the Project of Science and Technology Development Plan of Jilin Province under Grant Nos 20150204003GX and 20130206021GXthe Project of Science and Technology Plan of Changchun City under Grant No 14KG020
文摘We report fabrication and characterization of organic heterojunction UV detectors based on N,N＇-bis（naphthalen- 1-y1）-N,N＇-bis （phenyl） benzidine （NPB） and fullerene C60. The effects of different thicknesses of NPB and C60 layers are studied and compared. Notably, the optimal thicknesses of electron acceptor C60 and electron donor NPB are 40 nm and 80 nm, respectively. The J V characteristic curves of the device demonstrate a three-order- of-magnitude difference when illuminated under a 350nm UV light and in the dark at -0.5 V. The device exhibits high sensitivity in the region of 320-380nm with the peak located around 35Onm. Especially, it shows excellent photo-response characteristic with a responsivity as high as 315 mA/W under the illumination of 192μW.cm 2 350nm UV light at -5 V. These results indicate that the NPB/C60 heterojunction structure device might be used as low-cost low-voltage UV photodetectors.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61521064,61522408,61574169,61334007,61474136,and 61574166)the Ministry of Science and Technology of China(Grant Nos.2018YFB0406504,2016YFA0201803,2016YFA0203800,and 2017YFB0405603)+1 种基金the Key Research Program of Frontier Sciences of Chinese Academy of Sciences(Grant Nos.QYZDB-SSW-JSC048 and QYZDY-SSW-JSC001)the Beijing Municipal Science and Technology Project,China(Grant No.Z171100002017011)
文摘Ultraviolet(UV) photodetectors(PDs) have drawn great attention in recent years due to their potential application in civil and military fields. Because of its ultrawide bandgap, low cost, strong radiation hardness, and high thermal and chemical stability with high visible-light transparency, Ga_2O_3 is regarded as the most promising candidate for UV detection.Furthermore, the bandgap of Ga_2O_3 is as high as 4.7–4.9 eV, directly corresponding to the solar-blind UV detection band with wavelength less than 280 nm. There is no need of doping in Ga_2O_3 to tune its bandgap, compared to AlGaN, MgZnO,etc, thereby avoiding alloy composition fluctuations and phase separation. At present, solar-blind Ga_2O_3 photodetectors based on single crystal or amorphous Ga_2O_3 are mainly focused on metal–semiconductor–metal and Schottky photodiodes.In this work, the recent achievements of Ga_2O_3 photodetectors are systematically reviewed. The characteristics and performances of different photodetector structures based on single crystal Ga_2O_3 and amorphous Ga_2O_3 thin film are analyzed and compared. Finally, the prospects of Ga_2O_3 UV photodetectors are forecast.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61475153 and 61605200)the Jilin Province Young and Middle-aged Science and Technology Innovation Leaders and Team Project,China(Grant No.20180519023JH)+1 种基金the 100 Talents Program of the Chinese Academy of Sciencesthe Science Fund for Excellent Young Scholars of Jilin Province,China(Grant No.20180520173JH)
文摘Ultraviolet(UV) photodetectors have attracted more and more attention due to their great potential applications in missile tracking, flame detecting, pollution monitoring, ozone layer monitoring, and so on. Owing to the special characteristics of large bandgap, solution processable, low cost, environmentally friendly, etc., wide bandgap oxide semiconductor materials, such as ZnO, ZnMgO, Ga_2O_3, TiO_2, and Ni O, have gradually become a series of star materials in the field of semiconductor UV detection. In this paper, a review is presented on the development of UV photodetectors based on wide bandgap oxide semiconductor films.
基金supported by the National Natural Science Foundation of China(Grant Nos.61371046,61405026,61474016,and 61421002)China Postdoctoral Science Foundation(Grant No.2014M552330)
文摘We choose 8-hydroxyquinoline derivative-metal complexes（Beq,Mgq,and Znq） as the acceptors（A） and 4,4＇,4”-tri-（2-methylphenyl phenylamino） triphenylaine（m-MTDATA） as the donor（D） respectively to study the existing energy transfer process in the organic ultraviolet（UV） photodetector（PD）,which has an important influence on the sensitivity of PDs.The energy transfer process from D to A without exciplex formation is discussed,differing from the working mechanism of previous PDs with Gaq[Zisheng Su,Wenlian Li,Bei Chu,Tianle Li,Jianzhuo Zhu,Guang Zhang,Fei Yan,Xiao Li,Yiren Chen and Chun-Sing Lee 2008 Appl.Phys.Lett.93 103309）]and REq[J.B.Wang,W.L.Li,B.Chu,L.L.Chen,G.Zhang,Z.S.Su,Y.R.Chen,D.F.Yang,J.Z.Zhu,S.H.Wu,F.Yan,H.H.Liu,C.S.Lee 2010 Org.Electron.111301]used as an A material.Under 365-nm UV irradiation with an intensity of 1.2 mW/cm^2,the m-MTDATA：Beq blend device with a weight ratio of 1：1 shows a response of 192 mAAV with a detectivity of 6.5 × 10^（11） Jones,which exceeds those of PDs based on Mgq（146 mA/W） and Znq（182 mA/W） due to better energy level alignment between m-MTDATA/Beq and lower radiative decay.More photophysics processes of the PDs involved are discussed in detail.
基金supported by the National Natural Science Foun-dation of China(NSFC,52072207)Guizhou Provincial Science and Technology Projects(Grant Nos.ZK[2023]YB145,ZK[2023]YB149,and ZK[2022]214)+1 种基金Science and Technology Project of Guizhou Provincial Education Department(Grant Nos.[2022]143,[2022]150,and KY[2022]173)Science and Technology Foundation of Guizhou Minzu University(Grant Nos.GZMUZK[2022]YB21 and GZ-MUSYS[2021]02)。
文摘A self-powered ultraviolet photodetector(UV PD)with van der Waals(vdW)Schottky junction based on TiO_(2) nanorod arrays/Au-modulated V2 CTx MXene is reported.The Schottky junction enables the device to operate in self-powered mode.The dangling bond-free surface of V2 CTx MXene reduces the charge recombination at the junction interface.Meanwhile,V2 CTx MXene,with the work function(WF)increasing to 5.35 eV,forms a hole transport layer by contacting with Au electrode,which facilitates the carrier extraction.The electron lifetime in the device has prolonged to 8.95μs.As a result,the responsivity and detectivity of the PD have achieved 28 mA/W and 1.2×10^(11) cm Hz1/2/W(340 nm,65 mW/cm2,0 V),respectively.In addition,the presence of the Au electrode prevents the vanadium from coming into contact with oxygen and oxidizing,preserving the properties of the V2 CTx films.After 180 days of exposure to the atmosphere,the device performance remained at a particularly high level,indicating enhanced durability.This work points out an effective approach to modulate the properties of V2 CTx to obtain the high performance and stability of the UV PD.
基金Project supported by the Pre-Research Foundation from the National Ministries and Commissions(Nos.51323040118,513080302)
文摘A two-dimensional model of a 4H-SiC metal-semiconductor-metal（MSM） ultraviolet photodetector has been established using a self-consistent numerical calculation method.The structure-dependent spectral response of a 4H-SiC MSM detector is calculated by solving Poisson＇s equation,the current continuity equation and the current density equation.The calculated results are verified with experimental data.With consideration of the reflection and absorption on the metal contacts,a detailed study involving various electrode heights（H）,spacings （S） and widths（W） reveals conclusive results in device design.The mechanisms responsible for variations of responsivity with those parameters are analyzed.The findings show that responsivity is inversely proportional to electrode height and is enhanced with an increase of electrode spacing and width.In addition,the ultraviolet （UV）-to-visible rejection ratio is 103.By optimizing the device structure at 10 V bias,a responsivity as high as 180.056 mA/W,a comparable quantum efficiency of 77.93%and a maximum UV-to-visible rejection ratio of 1875 are achieved with a detector size of H = 50 nm,S =9μm and W = 3μm.
基金financially supported by the National Natural Science Foundation of China(11674265)the Natural Science Basic Research Project of Shaanxi Province(2018JZ6003)the Fundamental Research Funds for the Central Universities(3102019MS0402)。
文摘Ternary layered compound materials(bismuth oxyhalides and metal phosphorus trichalcogenides)stand out in electronic and optoelectronic fields due to their interesting physical properties.However,few studies focus on the preparation of high-quality two-dimensional(2D)BiOBr crystals with a typical layered structure,let alone their optoelectronic applications.Here,for the first time,high-quality 2D BiOBr crystals with ultrathin thicknesses(less than 10 nm)and large domain sizes(~100μm)were efficiently prepared via a modified space-confined chemical vapor deposition(SCCVD)method.It is demonstrated that a moderate amount of H2O molecules in the SCCVD system greatly promote the formation of high-quality 2D BiOBr crystals because of the strong polarity of H2O molecules.In addition,a linear relationship between the thickness of BiOBr nanosheets and Raman shift of A1g(1)mode was found.Corresponding theoretical calculations were carried out to verify the experimental data.Furthermore,the BiOBr-based photodetector was fabricated,exhibiting excellent performances with a responsivity of 12.4 A W-1 and a detectivity of 1.6×1013 Jones at 365 nm.This study paves the way for controllable preparation of high-quality 2D BiOBr crystals and implies intriguing opportunities of them in optoelectronic applications.
基金Project supported by the Pre-Research Foundation from the National Ministries and Commissions,China(Nos.51323040118, 513080302).
文摘Based on thermionic emission theory,a model of a 6H-SiC metal-semiconductor-metal（MSM） ultraviolet photodetector is established with the simulation package ISE-TCAD.A device with 3μm electrode width（W） and 3μm electrode spacing（L） is simulated.The findings show that the MSM photodetector has quite a low dark current of 15 pA at 10V bias and the photocurrent is two orders of magnitude higher than the dark current.The influences of different structures on dark and illuminated current-voltage characteristics of the MSM photodetector are investigated to optimize the device parameters.Simulation results indicate that the maximum photocurrent and the highest ratio of photocurrent to dark current at 15 V bias are 5.3 nA and 327 with device parameters of W=6μm,L=3μm and W =3μm,L=6μm,respectively.
基金acknowledge the National Natural Science Foundation(51922012,21633014)the MOST of China(Grant Nos.:2017YFA0204504,2018YFA0208502,,2018YFA0704803)+1 种基金Beijing Municipal Science and Technology(Z181100004418014)Youth Innovation Promotion Association CAS(2018034).
文摘Organic photochromic materials have drawn considerable attention for their potential applications in large-scale and low-cost optoelectronics owing to unique tunable physicochemical properties.For organic photodetectors,photochromic materials have realized optical and electrical engineering of semiconductor layers,which incorporate not only tunable performance,but also functionalities to optoelectronic devices.However,the essential challenge is to assemble large-area photochromic micro-and nanostructure arrays with controllable geometry and precise alignment,which restricts the integration of multifunctional optoelectronic devices.Herein,we fabricate organic photochromic one-dimensional(1D)arrays via a feasible solution process through the confined crystallization of organic molecules.By modulating and controlling the photoisomerization behaviors,these 1D photochromic arrays possess broad spectral tunability,which ensure tunable photoresponse.Furthermore,we investigate the crystallographic transition and electronic performance variation of these 1D photochromic arrays.By adjusting the dwell time of ultraviolet(UV)irradiation,the UV photochromic photodetectors realize tunable and repeatable responsivity from 85.6 to 0.709 mA/W.Our work provides new possibilities for optical and electrical engineering of photochromic microwires towards the integration of multifunctional optoelectronic devices.
基金Project supported by the Pre-Research Foundation from the National Ministries and Commissions of China(Nos.51323040118. 513080302)
文摘A novel semicircular electrode metal-semiconductor-metal（SEMSM） ultraviolet detector is modeled, investigated and characterized with a self-consistent numerical calculation method.For the purpose of model and performance verification,a comprehensive comparison of the SEMSM detector and a conventional electrode MSM detector is carried out with experimental data.The results indicate that the physical models are able to predict the enhanced device features.Moreover,the structural parameters have been adjusted appropriately to optimize the SEMSM detector.The findings show that a device with a 2μm finger radius and 3 /mi spacing exhibits outstanding characteristics in terms of a peak responsivity of 0.177 A/W at 290 nm,a maximum external quantum efficiency of over 75%,and a comparable normalized photocurrent to dark current ratio of 1.192×10^（-1） W^（-1） at 0.3 V bias. These results demonstrate that the SEMSM detector has excellent performance for optoelectronic integrated circuit applications.
基金supported by the Natural Science Foundation of Liaoning Province of China(Grant No.2013020010)
文摘By utilizing Schottky contact in device fabrication,we have constructed fast response ultraviolet photodetectors based on the solution-processed Zn O nanocrystals.At 5 V,the detector exhibits fast photoresponse with a rise time of 20 ns and fall time of 350 ns,which is one of the fastest response time among the reported Zn O-based photodetectors.The results reported in this paper may show great promise for fast response optoelectronic devices based on the solution-processed nanocrystals.
