The responsivity and the noise of a detector determine the sensitivity. Thermal energy usually affects both the responsivity and the noise spectral density. In this work, the noise characteristics and responsivity of ...The responsivity and the noise of a detector determine the sensitivity. Thermal energy usually affects both the responsivity and the noise spectral density. In this work, the noise characteristics and responsivity of an antenna-coupled AlGaN/GaN high-electron-mobility-transistor(HEMT) terahertz detector are evaluated at temperatures elevated from 300 K to 473 K. Noise spectrum measurement and a simultaneous measurement of the source–drain conductance and the terahertz photocurrent allow for detailed analysis of the electrical characteristics, the photoresponse, and the noise behavior. The responsivity is reduced from 59 mA/W to 11 mA/W by increasing the detector temperature from 300 K to 473 K. However,the noise spectral density maintains rather constantly around 1–2 pA/Hz^(1/2) at temperatures below 448 K, above which the noise spectrum abruptly shifts from Johnson-noise type into flicker-noise type and the noise density is increased up to one order of magnitude. The noise-equivalent power(NEP) is increased from 22 pW/Hz^(1/2) at 300 K to 60 pW/Hz^(1/2) at 448 K mainly due to the reduction in mobility. Above 448 K, the NEP is increased up to 1000 pW/Hz^(1/2) due to the strongly enhanced noise. The sensitivity can be recovered by cooling the detector back to room temperature.展开更多
Si-dopedβ-Ga_(2)O_(3)films are fabricated through metal-organic chemical vapor deposition(MOCVD).Solar-blind ultraviolet(UV)photodetector(PD)based on the films is fabricated by standard photolithography,and the photo...Si-dopedβ-Ga_(2)O_(3)films are fabricated through metal-organic chemical vapor deposition(MOCVD).Solar-blind ultraviolet(UV)photodetector(PD)based on the films is fabricated by standard photolithography,and the photodetection properties are investigated.The results show that the photocurrent increases to 11.2 mA under 200μW·cm^(-2)254 nm illumination and±20 V bias,leading to photo-responsivity as high as 788 A·W^(-1).The Si-dopedβ-Ga2O3-based PD is promised to perform solar-blind photodetection with high performance.展开更多
In this paper the temperature dependence of responsivity and response time for 6H-SiC ultraviolet （UV） photodetector is simulated based on numerical model in the range from 300 K to 900 K. The simulation results sho...In this paper the temperature dependence of responsivity and response time for 6H-SiC ultraviolet （UV） photodetector is simulated based on numerical model in the range from 300 K to 900 K. The simulation results show that the responsivity and the response time of device are less sensitive to temperature and this kind of UV photodetector has excellent temperature stability. Also the effects of device structure and bias voltage on the responsivity and the response time are presented. The thicker the drift region is, the higher the responsivity and the longer the response time are. So the thickness of drift region has to be carefully designed to make trade-off between responsivity and response time.展开更多
Strontium titanate(SrTiO3),which is a crucial perovskite oxide with a direct energy band gap of 3.2 eV,holds great promise for ultraviolet(UV)photodetection.However,the response performance of the conventional SrTiO3-...Strontium titanate(SrTiO3),which is a crucial perovskite oxide with a direct energy band gap of 3.2 eV,holds great promise for ultraviolet(UV)photodetection.However,the response performance of the conventional SrTiO3-based photodetectors is limited by the large relative dielectric constant of the material,which reduces the internal electric field for electron-hole pair separation to form a current collected by electrodes.Recently,graphene/semiconductor hybrid photodetectors by van-der-Waals heteroepitaxy method demonstrate ultrahigh sensitivity,which is benefit from the interface junction architecture and then prolonged lifetime of photoexcited carriers.Here,a graphene/SrTiO3 interface-based photodetector is demonstrated with an ultrahigh responsivity of 1.2×106 A/W at the wavelength of 325 nm and∼2.4×104 A/W at 261 nm.The corresponding response time is in the order of∼ms.Compared with graphene/GaN interface junctionbased hybrid photodetectors,∼2 orders of magnitude improvement of the ultrahigh responsivity originates from a gain mechanism which correlates with the large work function difference induced long photo-carrier lifetime as well as the low background carrier density.The performance of high responsivity and fast response speed facilitates SrTiO3 material for further efforts seeking practical applications.展开更多
In this paper, we have demonstrated a high performance waveguide photodiode integrated diluted waveguide serving as a fibre-to-waveguide coupler to achieve high coupling efficiency. High responsivity （〉 1 A/W）, hig...In this paper, we have demonstrated a high performance waveguide photodiode integrated diluted waveguide serving as a fibre-to-waveguide coupler to achieve high coupling efficiency. High responsivity （〉 1 A/W）, high saturation power （〉 45 mA） in the static state and extremely low dark current density （0.04 pA/μm2） with 3 dB bandwidth at 13.4 GHz have been achieved.展开更多
A graphene/AlGaN deep-ultraviolet(UV)photodetector is presented with ultrahigh responsivity of 3.4×105 A/W at 261 nm incident wavelength and 149 pW light power.A gain mechanism based on electron trapping at the p...A graphene/AlGaN deep-ultraviolet(UV)photodetector is presented with ultrahigh responsivity of 3.4×105 A/W at 261 nm incident wavelength and 149 pW light power.A gain mechanism based on electron trapping at the potential well is proposed to be responsible for the high responsivity.To optimize the trade-off between responsivity and response speed,a back-gate electrode is designed at the AlGaN/GaN two-dimensional electron gas(2DEG)area which eliminates the persistent photocurrent effect and shortens the recovery time from several hours to milliseconds.The 2DEG gate is proposed as an alternative way to apply the back gate electrode on AlGaN based devices on insulating substrates.This work sheds light on a possible way for weak deep-UV light detection.展开更多
A top-illuminated circular mesa uni-traveling-carrier photodetector（UTC-PD） is proposed in this paper. By employing Gaussian graded doping in In Ga As absorption layer and In P depleted layer, the responsivity and h...A top-illuminated circular mesa uni-traveling-carrier photodetector（UTC-PD） is proposed in this paper. By employing Gaussian graded doping in In Ga As absorption layer and In P depleted layer, the responsivity and high speed response characteristics of the device are optimized simultaneously. The responsivity up to 1.071 A/W（the external quantum efficiency of 86%） is obtained at 1550 nm with a 40-μm diameter device under 10-V reverse bias condition. Meanwhile, the dark current of 7.874 n A and the 3-d B bandwidth of 11 GHz are obtained with the same device at a reverse bias voltage of3 V.展开更多
We analyze the responsivity and signal-to-noise ratio(SNR)of a punchthrough enhanced phototransistor(PEPT).Measurement results show that the PEPT exhibits a good response to light over a wide range of intensity.Becaus...We analyze the responsivity and signal-to-noise ratio(SNR)of a punchthrough enhanced phototransistor(PEPT).Measurement results show that the PEPT exhibits a good response to light over a wide range of intensity.Because the responsivity is still as high as 106 A/W when the bias voltage is as low as 0.2 V,the device is suitable for ultra-low voltage applications.Meanwhile,with 1–10μA bias current,the PEPT shows the best performance for the responsivity and SNR.When incident light is as low as 3.8×10^(-8) W/cm^(2),the responsivity reaches approximately 108 A/W.The super high responsivity of PEPTs makes it possible to fabricate small sized photodetector.展开更多
The near-infrared responsivity of a silicon photodetector employing the impurity photovoltaic （IPV） effect is investigated with a numerical method. The improvement of the responsivity can reach 0.358 A/W at a wavele...The near-infrared responsivity of a silicon photodetector employing the impurity photovoltaic （IPV） effect is investigated with a numerical method. The improvement of the responsivity can reach 0.358 A/W at a wavelength of about 1200 nm, and its corresponding quantum efficiency is 41.1%. The origin of the enhanced responsivity is attributed to the absorption of sub-bandgap photons, which results in the carrier transition from the impurity energy level to the conduction band. The results indicate that the IPV effect may provide a general approach to enhancing the responsivity of photodetectors.展开更多
For the measurement of responsivity of an infrared photodetector,the most-used radiation source is a blackbody.In such a measurement system,distance between the blackbody,the photodetector and the aperture diameter ar...For the measurement of responsivity of an infrared photodetector,the most-used radiation source is a blackbody.In such a measurement system,distance between the blackbody,the photodetector and the aperture diameter are two parameters that contribute most measurement errors.In this work,we describe the configuration of our responsivity measurement system in great detail and present a method to calibrate the distance and aperture diameter.The core of this calibration method is to transfer direct measurements of these two parameters into an extraction procedure by fitting the experiment data to the calculated results.The calibration method is proved experimentally with a commercially extended InGaAs detector at a wide range of blackbody temperature,aperture diameter and distance.Then proof procedures are further extended into a detector fabricated in our laboratory and consistent results were obtained.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
A novel responsivity model, which is based on the solution of transport and continuity equation of carriers generated both in vertical and lateral PN junctions, is proposed for optical properties of stripe-shaped sili...A novel responsivity model, which is based on the solution of transport and continuity equation of carriers generated both in vertical and lateral PN junctions, is proposed for optical properties of stripe-shaped silicon ultraviolet (UV) photodiodes. With this model, the responsivity of the UV photodiode can be estimated. Fabricated in a standard 0.5 μm CMOS process, the measured spectral responsivity of the stripe-shaped UV photodiode shows a good match with the numerical simulation result of the responsivity model at the spectral of UV range. It means that the responsivity model, which is used for stripe-shaped UV photodiode, is reliable.展开更多
One of the most important parameter used for the evaluation of the energy rating of PV modules is, their spectral responsivities which are the measure of electrical performance parameters per incident solar radiation....One of the most important parameter used for the evaluation of the energy rating of PV modules is, their spectral responsivities which are the measure of electrical performance parameters per incident solar radiation. In this work, spectral responsivity measurements of a mono-crystalline, a poly-crystalline, a CIGS thin film and a bifacial module were measured using xenon-based flash type solar simulator system and a set of band pass filters. For the comprehensive characterization of parameters that may influence the spectral responsivity measurements, initially the simulator system was characterized both optically and thermally according to the IEC60904-9 and IEC60891 standard requirements. The optical characterizations in terms of spectral match, spatial non-uniformity and temporal instability indicate that the measured results (~3.0%, ~0.30% and ~0.20%) according to the IEC 60904-9 standard’s classification requirements correspond to A+A+A+ classes. Moreover, thermal characterizations in terms of the temperature uniformity show that over the 2 × 2 m area temperature uniformity of simulator system’s light distribution (1ºC) is almost two times better than the IEC 60891 standard requirements (±2ºC). Next, PV modules were electrically stabilized according to the IEC 61215-2 standard requirement’s (stability test) to reduce the fluctuations in their electrical performance parameters. Then, using the band pass filters, temperature controlled xenon-based solar simulator system and a reference PV module of the spectral responsivity of PV modules were measured from 400 nm to 1100 nm with 50 nm steps with relative uncertainty of 10<sup>-3</sup> level.展开更多
Even though efficient near-infrared(NIR)detection is critical for numerous applications,state-of-the-art NIR detectors either suffer from limited capability of detecting incoming photons,i.e.,have poor spectral respon...Even though efficient near-infrared(NIR)detection is critical for numerous applications,state-of-the-art NIR detectors either suffer from limited capability of detecting incoming photons,i.e.,have poor spectral responsivity,or are made of expensive groupⅢ-Ⅴnon-CMOS compatible materials.Here we present a nanoengineered PIN-photodiode made of CMOS-compatible germanium(Ge)that achieves a verified external quantum efficiency(EQE)above 90%over a wide wavelength range(1.2-1.6μm)at zero bias voltage at room temperature.For instance,at 1.55μm,this corresponds to a responsivity of 1.15 A/W.In addition to the excellent spectral responsivity at NIR,the performance at visible and ultraviolet wavelengths remains high(EQE exceeds even 100%below 300 nm)resulting in an exceptionally wide spectral response range.The high performance is achieved by minimizing optical losses using surface nanostructures and electrical losses using both conformal atomic-layer-deposited aluminum oxide surface passivation and dielectric induced electric field-based carrier collection instead of conventional pn-junction.The dark current density of 76μA/cm2 measured at a reverse bias of 5 V is lower than previously reported for Ge photodiodes.The presented results should have an immediate impact on the design and manufacturing of Ge photodiodes and NIR detection in general.展开更多
The surging demand and adoption of infrared photodetectors(IRPDs)in sectors of imaging,mobile,healthcare,automobiles,and optical communication are hindered by the prohibitive costs of traditional IRPD materials such a...The surging demand and adoption of infrared photodetectors(IRPDs)in sectors of imaging,mobile,healthcare,automobiles,and optical communication are hindered by the prohibitive costs of traditional IRPD materials such as InGaAs and HgCdTe.Quantum dots(QDs),especially lead chalcogenide(PbS)QDs,represent the next-generation lowbandgap semiconductors for near-infrared(NIR)detection due to their high optical absorption coefficient,tunable bandgap,low fabrication costs,and device compatibility.Innovative techniques such as ligand exchange processes have been proposed to boost the performance of PbS QDs photodetectors,mostly using short ligands like 1,2-ethanedithiol(EDT)and tetrabutylammonium iodide(TBAI).Our study explores the use of long-chain dithiol ligands to enhance the responsivity of PbS QDs/InGaZnO phototransistors.Long-chain dithiol ligands are found to suppress horizontal electron transport/leakage and electron trapping,which is beneficial for responsivity.Utilizing a novel ligand-exchange technique with 1,10-decanedithiol(DDT),we develop high-performance hybrid phototransistors with detectivity exceeding 10^(14) Jones.Based on these phototransistors,we demonstrate image communication through a NIR optical communication system.The long-ligand PbS QDs/InGaZnO hybrid phototransistor demonstrates significant potential for NIR low-dose imaging and optical communication,particularly in scenarios requiring the detection of weak light signals at low frequencies.展开更多
The wide-bandgap semiconductor material Ga_(2)O_(3) exhibits great potential in solar-blind deep-ultraviolet(DUV)photodetection applications,including none-line-of-sight secure optical communication,fire warning,high-...The wide-bandgap semiconductor material Ga_(2)O_(3) exhibits great potential in solar-blind deep-ultraviolet(DUV)photodetection applications,including none-line-of-sight secure optical communication,fire warning,high-voltage electricity monitoring,and maritime fog dispersion navigation.However,Ga_(2)O_(3) photodetectors have traditionally faced challenges in achieving both high responsivity and fast response time,limiting their practical application.Herein,the Ga_(2)O_(3) solar-blind DUV photodetectors with a suspended structure have been constructed for the first time.The photodetector exhibits a high responsivity of 1.51×10^(10) A/W,a sensitive detectivity of 6.01×10^(17) Jones,a large external quantum efficiency of 7.53×10^(12)%,and a fast rise time of 180 ms under 250-nm illumination.Notably,the photodetector achieves both high responsivity and fast response time simultaneously under ultra-weak power intensity excitation of 0.01μW/cm^(2).This important improvement is attributed to the reduction of interface defects,improved carrier transport,efficient carrier separation,and enhanced light absorption enabled by the suspended structure.This work provides valuable insights for designing and optimizing high-performance Ga_(2)O_(3) solar-blind photodetectors.展开更多
Graphene is a very attractive material for broadband photodetection in hyperspectral imaging and sensing systems.However,its potential use has been hindered by tradeoffs between the responsivity,bandwidth,and operatio...Graphene is a very attractive material for broadband photodetection in hyperspectral imaging and sensing systems.However,its potential use has been hindered by tradeoffs between the responsivity,bandwidth,and operation speed of existing graphene photodetectors.Here,we present engineered photoconductive nanostructures based on goldpatched graphene nano-stripes,which enable simultaneous broadband and ultrafast photodetection with high responsivity.These nanostructures merge the advantages of broadband optical absorption,ultrafast photocarrier transport,and carrier multiplication within graphene nano-stripes with the ultrafast transport of photocarriers to gold patches before recombination.Through this approach,high-responsivity operation is realized without the use of bandwidth-limiting and speed-limiting quantum dots,defect states,or tunneling barriers.We demonstrate highresponsivity photodetection from the visible to infrared regime(0.6 A/W at 0.8μm and 11.5 A/W at 20μm),with operation speeds exceeding 50 GHz.Our results demonstrate improvement of the response times by more than seven orders of magnitude and an increase in bandwidths of one order of magnitude compared to those of higherresponsivity graphene photodetectors based on quantum dots and tunneling barriers.展开更多
Graphene has attracted great interest in optoelectronics, owing to its high carrier mobility and broadband absorption. However, a graphene photodetector exhibits low photoresponsivity because of its weak light absorpt...Graphene has attracted great interest in optoelectronics, owing to its high carrier mobility and broadband absorption. However, a graphene photodetector exhibits low photoresponsivity because of its weak light absorption. In this work, we designed a graphene/MoSe_2 heterostructure photodetector, which exhibits photoresponse ranging from visible to near infrared and an ultrahigh photoresponsivity up to 1.3 × 104 A·W^(-1) at 550 nm. The electron–hole pairs are excited in a few-layered MoSe2 and separated by the built-in electric field. A large number of electrons shift to graphene, while the holes remain in the MoSe_2, which creates a photogating effect.展开更多
Two-dimensional materials are attractive for constructing high-performance photonic chip-integrated photodetectors because of their remarkable electronic and optical properties and dangling-bond-free surfaces.However,...Two-dimensional materials are attractive for constructing high-performance photonic chip-integrated photodetectors because of their remarkable electronic and optical properties and dangling-bond-free surfaces.However,the reported chip-integrated two-dimensional material photodetectors were mainly implemented with the configuration of metalsemiconductor-metal,suffering from high dark currents and low responsivities at high operation speed.Here,we report a van der Waals PN heterojunction photodetector,composed of p-type black phosphorous and n-type molybdenum telluride,integrated on a silicon nitride waveguide.The built-in electric field of the PN heterojunction significantly suppresses the dark current and improves the responsivity.Under a bias of 1 V pointing from n-type molybdenum telluride to p-type black phosphorous,the dark current is lower than 7 nA,which is more than two orders of magnitude lower than those reported in other waveguide-integrated black phosphorus photodetectors.An intrinsic responsivity up to 577 mA W^(−1) is obtained.Remarkably,the van der Waals PN heterojunction is tunable by the electrostatic doping to further engineer its rectification and improve the photodetection,enabling an increased responsivity of 709 mA W^(−1).Besides,the heterojunction photodetector exhibits a response bandwidth of~1.0 GHz and a uniform photodetection over a wide spectral range,as experimentally measured from 1500 to 1630 nm.The demonstrated chip-integrated van der Waals PN heterojunction photodetector with low dark current,high responsivity and fast response has great potentials to develop high-performance on-chip photodetectors for various photonic integrated circuits based on silicon,lithium niobate,polymer,etc.展开更多
4H-SiC based metal-semiconductor-metal (MSM) photodetectors with diverse spacing were designed, fabricated, and characterized, in which nickel Schottky contacts were needed. Current-voltage and spectral responsivity m...4H-SiC based metal-semiconductor-metal (MSM) photodetectors with diverse spacing were designed, fabricated, and characterized, in which nickel Schottky contacts were needed. Current-voltage and spectral responsivity measurements were carried out at room temperature. The fabricated 4 μm-spacing device showed a very low dark current (0.25 pA at 5 V bias voltage), a typical responsivity of 0.103 A/W at 20 V, and a peak re-sponse wavelength at 290 nm. The fabricated devices held a high DUV to visible re-jection ratio of >103.展开更多
基金Project supported by the National Key Research and Development Program of China(Grant No.2016YFF0100501)the National Natural Science Foundation of China(Grant Nos.61771466,61775231,and 61611530708)+1 种基金the Six Talent Peaks of Jiangsu Province,China(Grant No.XXRJ-079)the Youth Innovation Promotion Association of Chinese Academy of Sciences(Grant No.2017372)
文摘The responsivity and the noise of a detector determine the sensitivity. Thermal energy usually affects both the responsivity and the noise spectral density. In this work, the noise characteristics and responsivity of an antenna-coupled AlGaN/GaN high-electron-mobility-transistor(HEMT) terahertz detector are evaluated at temperatures elevated from 300 K to 473 K. Noise spectrum measurement and a simultaneous measurement of the source–drain conductance and the terahertz photocurrent allow for detailed analysis of the electrical characteristics, the photoresponse, and the noise behavior. The responsivity is reduced from 59 mA/W to 11 mA/W by increasing the detector temperature from 300 K to 473 K. However,the noise spectral density maintains rather constantly around 1–2 pA/Hz^(1/2) at temperatures below 448 K, above which the noise spectrum abruptly shifts from Johnson-noise type into flicker-noise type and the noise density is increased up to one order of magnitude. The noise-equivalent power(NEP) is increased from 22 pW/Hz^(1/2) at 300 K to 60 pW/Hz^(1/2) at 448 K mainly due to the reduction in mobility. Above 448 K, the NEP is increased up to 1000 pW/Hz^(1/2) due to the strongly enhanced noise. The sensitivity can be recovered by cooling the detector back to room temperature.
基金the National Natural Science Foundation of China(Grant Nos.61774019 and 51572033)the Fund of State Key Laboratory of Information Photonics and Optical Communications(BUPT)the Fundamental Research Funds for the Central Universities,China.
文摘Si-dopedβ-Ga_(2)O_(3)films are fabricated through metal-organic chemical vapor deposition(MOCVD).Solar-blind ultraviolet(UV)photodetector(PD)based on the films is fabricated by standard photolithography,and the photodetection properties are investigated.The results show that the photocurrent increases to 11.2 mA under 200μW·cm^(-2)254 nm illumination and±20 V bias,leading to photo-responsivity as high as 788 A·W^(-1).The Si-dopedβ-Ga2O3-based PD is promised to perform solar-blind photodetection with high performance.
文摘In this paper the temperature dependence of responsivity and response time for 6H-SiC ultraviolet （UV） photodetector is simulated based on numerical model in the range from 300 K to 900 K. The simulation results show that the responsivity and the response time of device are less sensitive to temperature and this kind of UV photodetector has excellent temperature stability. Also the effects of device structure and bias voltage on the responsivity and the response time are presented. The thicker the drift region is, the higher the responsivity and the longer the response time are. So the thickness of drift region has to be carefully designed to make trade-off between responsivity and response time.
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2017YFF0104801 and 2018YFB0406601)the National Natural Science Foundation of China(Grant Nos.61804012 and 11721404).
文摘Strontium titanate(SrTiO3),which is a crucial perovskite oxide with a direct energy band gap of 3.2 eV,holds great promise for ultraviolet(UV)photodetection.However,the response performance of the conventional SrTiO3-based photodetectors is limited by the large relative dielectric constant of the material,which reduces the internal electric field for electron-hole pair separation to form a current collected by electrodes.Recently,graphene/semiconductor hybrid photodetectors by van-der-Waals heteroepitaxy method demonstrate ultrahigh sensitivity,which is benefit from the interface junction architecture and then prolonged lifetime of photoexcited carriers.Here,a graphene/SrTiO3 interface-based photodetector is demonstrated with an ultrahigh responsivity of 1.2×106 A/W at the wavelength of 325 nm and∼2.4×104 A/W at 261 nm.The corresponding response time is in the order of∼ms.Compared with graphene/GaN interface junctionbased hybrid photodetectors,∼2 orders of magnitude improvement of the ultrahigh responsivity originates from a gain mechanism which correlates with the large work function difference induced long photo-carrier lifetime as well as the low background carrier density.The performance of high responsivity and fast response speed facilitates SrTiO3 material for further efforts seeking practical applications.
基金Project supported by the National High Technology Research and Development Program of China(Grant No.2006CB302802)
文摘In this paper, we have demonstrated a high performance waveguide photodiode integrated diluted waveguide serving as a fibre-to-waveguide coupler to achieve high coupling efficiency. High responsivity （〉 1 A/W）, high saturation power （〉 45 mA） in the static state and extremely low dark current density （0.04 pA/μm2） with 3 dB bandwidth at 13.4 GHz have been achieved.
基金Project supported by the Research Innovation Fund for College Students of Beijing University of Posts and Telecommunications(Grant No.202002046)the National Natural Science Foundation of China(Grant No.61804012).
文摘A graphene/AlGaN deep-ultraviolet(UV)photodetector is presented with ultrahigh responsivity of 3.4×105 A/W at 261 nm incident wavelength and 149 pW light power.A gain mechanism based on electron trapping at the potential well is proposed to be responsible for the high responsivity.To optimize the trade-off between responsivity and response speed,a back-gate electrode is designed at the AlGaN/GaN two-dimensional electron gas(2DEG)area which eliminates the persistent photocurrent effect and shortens the recovery time from several hours to milliseconds.The 2DEG gate is proposed as an alternative way to apply the back gate electrode on AlGaN based devices on insulating substrates.This work sheds light on a possible way for weak deep-UV light detection.
基金Project supported partially by the National Natural Science Foundation of China(Grant Nos.61274044 and 61077049)the National Basic Research Program of China(Grant No.2010CB327600)+3 种基金the Program of Key International Science and Technology Cooperation Projects,China(Grant No.2011RR000100)the 111 Project of China(Grant No.B07005)the Specialized Research Fund for the Doctoral Program of China(Grant No.20130005130001)the Natural Science Foundation of Beijing,China(Grant No.4132069)
文摘A top-illuminated circular mesa uni-traveling-carrier photodetector（UTC-PD） is proposed in this paper. By employing Gaussian graded doping in In Ga As absorption layer and In P depleted layer, the responsivity and high speed response characteristics of the device are optimized simultaneously. The responsivity up to 1.071 A/W（the external quantum efficiency of 86%） is obtained at 1550 nm with a 40-μm diameter device under 10-V reverse bias condition. Meanwhile, the dark current of 7.874 n A and the 3-d B bandwidth of 11 GHz are obtained with the same device at a reverse bias voltage of3 V.
基金Supported by the National Natural Science Foundation of China under Grant Nos 61076046 and 61106003the Science and Technology Development Plan Projects of Jilin Province(No 20100501)。
文摘We analyze the responsivity and signal-to-noise ratio(SNR)of a punchthrough enhanced phototransistor(PEPT).Measurement results show that the PEPT exhibits a good response to light over a wide range of intensity.Because the responsivity is still as high as 106 A/W when the bias voltage is as low as 0.2 V,the device is suitable for ultra-low voltage applications.Meanwhile,with 1–10μA bias current,the PEPT shows the best performance for the responsivity and SNR.When incident light is as low as 3.8×10^(-8) W/cm^(2),the responsivity reaches approximately 108 A/W.The super high responsivity of PEPTs makes it possible to fabricate small sized photodetector.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61464007,61306084,and 51361022)the Postdoctoral Science Foundation of Jiangxi Province,China(Grant No.2014KY32)the Natural Science Foundation of Jiangxi Province,China(Grant No.20122BAB202002)
文摘The near-infrared responsivity of a silicon photodetector employing the impurity photovoltaic （IPV） effect is investigated with a numerical method. The improvement of the responsivity can reach 0.358 A/W at a wavelength of about 1200 nm, and its corresponding quantum efficiency is 41.1%. The origin of the enhanced responsivity is attributed to the absorption of sub-bandgap photons, which results in the carrier transition from the impurity energy level to the conduction band. The results indicate that the IPV effect may provide a general approach to enhancing the responsivity of photodetectors.
基金This work was supported by the National Key Technologies R&D Program of China(No.2019YFA0705203,2019YFA070104)the National Natural Science Foundation of China(No.62004189)the State Key Laboratory of Special Rare Metal Materials,Northwest Rare Metal Materials Research Institute(No.SKL2023K00X).
文摘For the measurement of responsivity of an infrared photodetector,the most-used radiation source is a blackbody.In such a measurement system,distance between the blackbody,the photodetector and the aperture diameter are two parameters that contribute most measurement errors.In this work,we describe the configuration of our responsivity measurement system in great detail and present a method to calibrate the distance and aperture diameter.The core of this calibration method is to transfer direct measurements of these two parameters into an extraction procedure by fitting the experiment data to the calculated results.The calibration method is proved experimentally with a commercially extended InGaAs detector at a wide range of blackbody temperature,aperture diameter and distance.Then proof procedures are further extended into a detector fabricated in our laboratory and consistent results were obtained.
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.
文摘A novel responsivity model, which is based on the solution of transport and continuity equation of carriers generated both in vertical and lateral PN junctions, is proposed for optical properties of stripe-shaped silicon ultraviolet (UV) photodiodes. With this model, the responsivity of the UV photodiode can be estimated. Fabricated in a standard 0.5 μm CMOS process, the measured spectral responsivity of the stripe-shaped UV photodiode shows a good match with the numerical simulation result of the responsivity model at the spectral of UV range. It means that the responsivity model, which is used for stripe-shaped UV photodiode, is reliable.
文摘One of the most important parameter used for the evaluation of the energy rating of PV modules is, their spectral responsivities which are the measure of electrical performance parameters per incident solar radiation. In this work, spectral responsivity measurements of a mono-crystalline, a poly-crystalline, a CIGS thin film and a bifacial module were measured using xenon-based flash type solar simulator system and a set of band pass filters. For the comprehensive characterization of parameters that may influence the spectral responsivity measurements, initially the simulator system was characterized both optically and thermally according to the IEC60904-9 and IEC60891 standard requirements. The optical characterizations in terms of spectral match, spatial non-uniformity and temporal instability indicate that the measured results (~3.0%, ~0.30% and ~0.20%) according to the IEC 60904-9 standard’s classification requirements correspond to A+A+A+ classes. Moreover, thermal characterizations in terms of the temperature uniformity show that over the 2 × 2 m area temperature uniformity of simulator system’s light distribution (1ºC) is almost two times better than the IEC 60891 standard requirements (±2ºC). Next, PV modules were electrically stabilized according to the IEC 61215-2 standard requirement’s (stability test) to reduce the fluctuations in their electrical performance parameters. Then, using the band pass filters, temperature controlled xenon-based solar simulator system and a reference PV module of the spectral responsivity of PV modules were measured from 400 nm to 1100 nm with 50 nm steps with relative uncertainty of 10<sup>-3</sup> level.
基金partially funded through the ATTRACT project funded by the European Union’s Horizon 2020 research and innovation programme under grant agreement No.101004462by Business Finland(Project No.RaPtor 687/31/2019)+1 种基金by the Academy of Finland(Project Nos.328482 and 331313)by Tandem Industry Academia funding from the Finnish Research Impact Foundation.
文摘Even though efficient near-infrared(NIR)detection is critical for numerous applications,state-of-the-art NIR detectors either suffer from limited capability of detecting incoming photons,i.e.,have poor spectral responsivity,or are made of expensive groupⅢ-Ⅴnon-CMOS compatible materials.Here we present a nanoengineered PIN-photodiode made of CMOS-compatible germanium(Ge)that achieves a verified external quantum efficiency(EQE)above 90%over a wide wavelength range(1.2-1.6μm)at zero bias voltage at room temperature.For instance,at 1.55μm,this corresponds to a responsivity of 1.15 A/W.In addition to the excellent spectral responsivity at NIR,the performance at visible and ultraviolet wavelengths remains high(EQE exceeds even 100%below 300 nm)resulting in an exceptionally wide spectral response range.The high performance is achieved by minimizing optical losses using surface nanostructures and electrical losses using both conformal atomic-layer-deposited aluminum oxide surface passivation and dielectric induced electric field-based carrier collection instead of conventional pn-junction.The dark current density of 76μA/cm2 measured at a reverse bias of 5 V is lower than previously reported for Ge photodiodes.The presented results should have an immediate impact on the design and manufacturing of Ge photodiodes and NIR detection in general.
基金the EPSRC SWIMS(EP/V039717/1)Royal Society(RGS\R1\221009 and IEC\NSFC\211201)+4 种基金Leverhulme Trust(RPG-6062022-263)Sêr Cymru programme-Enhancing Competitiveness Equipment Awards 2022-23(MA/VG/2715/22-PN66)the financial support from National Natural Science Foundation of China(NSFC)Grant No.62105214the financial support from National Natural Science Foundation of China(NSFC)No.61974006Shenzhen Science and Technology Innovation Committee(KJZD20230923113759002 and GJHZ20240218113959009).
文摘The surging demand and adoption of infrared photodetectors(IRPDs)in sectors of imaging,mobile,healthcare,automobiles,and optical communication are hindered by the prohibitive costs of traditional IRPD materials such as InGaAs and HgCdTe.Quantum dots(QDs),especially lead chalcogenide(PbS)QDs,represent the next-generation lowbandgap semiconductors for near-infrared(NIR)detection due to their high optical absorption coefficient,tunable bandgap,low fabrication costs,and device compatibility.Innovative techniques such as ligand exchange processes have been proposed to boost the performance of PbS QDs photodetectors,mostly using short ligands like 1,2-ethanedithiol(EDT)and tetrabutylammonium iodide(TBAI).Our study explores the use of long-chain dithiol ligands to enhance the responsivity of PbS QDs/InGaZnO phototransistors.Long-chain dithiol ligands are found to suppress horizontal electron transport/leakage and electron trapping,which is beneficial for responsivity.Utilizing a novel ligand-exchange technique with 1,10-decanedithiol(DDT),we develop high-performance hybrid phototransistors with detectivity exceeding 10^(14) Jones.Based on these phototransistors,we demonstrate image communication through a NIR optical communication system.The long-ligand PbS QDs/InGaZnO hybrid phototransistor demonstrates significant potential for NIR low-dose imaging and optical communication,particularly in scenarios requiring the detection of weak light signals at low frequencies.
基金support from the China Postdoctoral Science Foundation(2023M742732)the Postdoctoral Fellowship Program of CPSF under grant number GZC20241303+3 种基金the Fundamental Research Funds for the Central Universities(XJSJ24100)the National Key R&D Program of China(2023YFB4402303)the National Natural Science Foundation of China(grant nos.62404176,62025402,62090033,92364204,9226420,and 62293522)Major Program of Zhejiang Natural Science Foundation(grant no.LDT23F04024F04).
文摘The wide-bandgap semiconductor material Ga_(2)O_(3) exhibits great potential in solar-blind deep-ultraviolet(DUV)photodetection applications,including none-line-of-sight secure optical communication,fire warning,high-voltage electricity monitoring,and maritime fog dispersion navigation.However,Ga_(2)O_(3) photodetectors have traditionally faced challenges in achieving both high responsivity and fast response time,limiting their practical application.Herein,the Ga_(2)O_(3) solar-blind DUV photodetectors with a suspended structure have been constructed for the first time.The photodetector exhibits a high responsivity of 1.51×10^(10) A/W,a sensitive detectivity of 6.01×10^(17) Jones,a large external quantum efficiency of 7.53×10^(12)%,and a fast rise time of 180 ms under 250-nm illumination.Notably,the photodetector achieves both high responsivity and fast response time simultaneously under ultra-weak power intensity excitation of 0.01μW/cm^(2).This important improvement is attributed to the reduction of interface defects,improved carrier transport,efficient carrier separation,and enhanced light absorption enabled by the suspended structure.This work provides valuable insights for designing and optimizing high-performance Ga_(2)O_(3) solar-blind photodetectors.
基金support from the Department of Energy(grant#DE-SC0016925)。
文摘Graphene is a very attractive material for broadband photodetection in hyperspectral imaging and sensing systems.However,its potential use has been hindered by tradeoffs between the responsivity,bandwidth,and operation speed of existing graphene photodetectors.Here,we present engineered photoconductive nanostructures based on goldpatched graphene nano-stripes,which enable simultaneous broadband and ultrafast photodetection with high responsivity.These nanostructures merge the advantages of broadband optical absorption,ultrafast photocarrier transport,and carrier multiplication within graphene nano-stripes with the ultrafast transport of photocarriers to gold patches before recombination.Through this approach,high-responsivity operation is realized without the use of bandwidth-limiting and speed-limiting quantum dots,defect states,or tunneling barriers.We demonstrate highresponsivity photodetection from the visible to infrared regime(0.6 A/W at 0.8μm and 11.5 A/W at 20μm),with operation speeds exceeding 50 GHz.Our results demonstrate improvement of the response times by more than seven orders of magnitude and an increase in bandwidths of one order of magnitude compared to those of higherresponsivity graphene photodetectors based on quantum dots and tunneling barriers.
基金financially supported by the National Natural Science Foundation of China(No.61575010)the Natural Science Foundation of Beijing(No.4162016)+1 种基金the Beijing Municipal Science and Technology Commission(No.Z151100003315018)the Beijing Nova Program(No.Z141109001814053)
文摘Graphene has attracted great interest in optoelectronics, owing to its high carrier mobility and broadband absorption. However, a graphene photodetector exhibits low photoresponsivity because of its weak light absorption. In this work, we designed a graphene/MoSe_2 heterostructure photodetector, which exhibits photoresponse ranging from visible to near infrared and an ultrahigh photoresponsivity up to 1.3 × 104 A·W^(-1) at 550 nm. The electron–hole pairs are excited in a few-layered MoSe2 and separated by the built-in electric field. A large number of electrons shift to graphene, while the holes remain in the MoSe_2, which creates a photogating effect.
基金supported by the National Key R&D Program of China(Grant Nos.2018YFA0307200 and 2017YFA0303800)the National Natural Science Foundation of China(Grant Nos.61905198,61775183,11634010,and 61675171)+1 种基金Key Research and Development Program in Shaanxi Province of China(Grant Nos.2017KJXX-12,2018JM1058,and 2018KW-009)the Fundamental Research Funds for the Central Universities(Grant Nos.3102017jc01001,3102018jcc034,and 3102017HQZZ022)。
文摘Two-dimensional materials are attractive for constructing high-performance photonic chip-integrated photodetectors because of their remarkable electronic and optical properties and dangling-bond-free surfaces.However,the reported chip-integrated two-dimensional material photodetectors were mainly implemented with the configuration of metalsemiconductor-metal,suffering from high dark currents and low responsivities at high operation speed.Here,we report a van der Waals PN heterojunction photodetector,composed of p-type black phosphorous and n-type molybdenum telluride,integrated on a silicon nitride waveguide.The built-in electric field of the PN heterojunction significantly suppresses the dark current and improves the responsivity.Under a bias of 1 V pointing from n-type molybdenum telluride to p-type black phosphorous,the dark current is lower than 7 nA,which is more than two orders of magnitude lower than those reported in other waveguide-integrated black phosphorus photodetectors.An intrinsic responsivity up to 577 mA W^(−1) is obtained.Remarkably,the van der Waals PN heterojunction is tunable by the electrostatic doping to further engineer its rectification and improve the photodetection,enabling an increased responsivity of 709 mA W^(−1).Besides,the heterojunction photodetector exhibits a response bandwidth of~1.0 GHz and a uniform photodetection over a wide spectral range,as experimentally measured from 1500 to 1630 nm.The demonstrated chip-integrated van der Waals PN heterojunction photodetector with low dark current,high responsivity and fast response has great potentials to develop high-performance on-chip photodetectors for various photonic integrated circuits based on silicon,lithium niobate,polymer,etc.
文摘4H-SiC based metal-semiconductor-metal (MSM) photodetectors with diverse spacing were designed, fabricated, and characterized, in which nickel Schottky contacts were needed. Current-voltage and spectral responsivity measurements were carried out at room temperature. The fabricated 4 μm-spacing device showed a very low dark current (0.25 pA at 5 V bias voltage), a typical responsivity of 0.103 A/W at 20 V, and a peak re-sponse wavelength at 290 nm. The fabricated devices held a high DUV to visible re-jection ratio of >103.
