We investigate the polarization-induced doping in the gradient variation of Al composition in the pAl_(0.75)Ga_(0.25)N/Al_xGa_(1-x)N hole injection layer(HIL)for deep ultraviolet light-emitting diodes(DUV-LEDs)with an...We investigate the polarization-induced doping in the gradient variation of Al composition in the pAl_(0.75)Ga_(0.25)N/Al_xGa_(1-x)N hole injection layer(HIL)for deep ultraviolet light-emitting diodes(DUV-LEDs)with an ultrathin p-GaN(4 nm)ohmic contact layer capable of emitting 277 nm.The experimental results show that the external quantum efficiency(EQE)and wall plug efficiency(WPE)of the structure graded from 0.75 to 0.55 in the HIL reach 5.49%and 5.04%,which are improved significantly by 182%and 209%,respectively,compared with the structure graded from 0.75 to 0.45,exhibiting a tremendous improvement.Both theoretical speculations and simulation results support that the larger the difference between 0.75 and x in the HIL,the higher the hole concentration that should be induced;thus,the DUV-LED has a higher internal quantum efficiency(IQE).Meanwhile,as the value of x decreases,the absorption of the DUV light emitted from the active region by the HIL is enhanced,reducing the light extraction efficiency(LEE).The IQE and LEE together affect the EQE performance of DUV-LEDs.To trade off the contradiction between the enhanced IQE and decreased LEE caused by the decrease in Al composition,the Al composition in the HIL was optimized through theoretical calculations and experiments.展开更多
We successfully fabricate a high performanceβ-phase(In_(0.09)Ga_(0.91))_(2)O_(3)single-crystalline film deep ultraviolet(DUV)solar-blind photodetector.The 2-inches high crystalline quality film is hetero-grown on the...We successfully fabricate a high performanceβ-phase(In_(0.09)Ga_(0.91))_(2)O_(3)single-crystalline film deep ultraviolet(DUV)solar-blind photodetector.The 2-inches high crystalline quality film is hetero-grown on the sapphire substrates using the plasma-assisted molecular beam epitaxy(PA-MBE).The smooth InGaO single crystalline film is used to construct the solar-blind DUV detector,which utilized an interdigitated Ti/Au electrode with a metal-semiconductor-metal structure.The device exhibits a low dark current of 40 pA(0 V),while its UV photon responsivity exceeds 450 A/W(50 V)at the peak wavelength of 232 nm with illumination intensity of 0.21 m W/cm^(2)and the UV/VIS rejection ratio(R232 nm/R380 nm)exceeds 4×10^(4).Furthermore,the devices demonstrate ultrafast transient characteristics for DUV signals,with fast-rising and fast-falling times of 80 ns and 420 ns,respectively.This excellent temporal dynamic behavior can be attributed to indium doping can adjust the electronic structure of Ga_(2)O_(3)alloys to enhance the performance of InGaO solar-blind detectors.Additionally,a two-dimensional DUV scanning image is captured using the InGaO photodetector as a sensor in an imaging system.Our results pave the way for future applications of two-dimensional array DUV photodetectors based on the large-scale InGaO heteroepitaxially grown alloy wide bandgap semiconductor films.展开更多
Coherent light with orbital angular momentum(OAM)is of great interest.Recently,OAM light generation by coupling a relativistic electron beam with a Gaussian mode laser pulse at the high harmonics of a helical undulato...Coherent light with orbital angular momentum(OAM)is of great interest.Recently,OAM light generation by coupling a relativistic electron beam with a Gaussian mode laser pulse at the high harmonics of a helical undulator has been demonstrated experimentally.In this paper,the possibility of delivering coherent OAM light at the 3^(rd)harmonic of the Gaussian mode seed laser is discussed for the Shanghai deep ultraviolet freeelectron laser(SDUV-FEL).Considerations are given on the experiment setup,the expected performance and the possible measurement method.展开更多
We develop a picosecond widely tunable laser in a deep-ultraviolet region from 175 nm to 210 nm, generated by two stages of frequency doubling of a 80-MHz mode-locked picosecond Ti：sapphire laser. A β-BaB2O4 walk-of...We develop a picosecond widely tunable laser in a deep-ultraviolet region from 175 nm to 210 nm, generated by two stages of frequency doubling of a 80-MHz mode-locked picosecond Ti：sapphire laser. A β-BaB2O4 walk-off compensation configuration and a KBe2BO3F2 prism-coupled device are adopted for the generation of second harmonic and fourth harmonics, respectively. The highest power is 3.72 mW at 193 nm, and the fluctuation at 2.85 mW in 130 rain is less than ±2%.展开更多
The localized surface plasmon resonance properties of Al and Alcore/Al2O3shell nanosphere dimers with Al and Al core nanosphere radii of 20 nm and Al2O3 shell of 2 nm in the deep-ultraviolet region have been studied u...The localized surface plasmon resonance properties of Al and Alcore/Al2O3shell nanosphere dimers with Al and Al core nanosphere radii of 20 nm and Al2O3 shell of 2 nm in the deep-ultraviolet region have been studied using the finite difference time domain method. The extinction spectra and the electric field distribution profiles of the two dimers for various gap distances between two individual nanospheres are compared with those of the corresponding monomers to reveal the extent of plasmon coupling. It is found that with the interparticle distance decreasing, a strong plasmon coupling between two Al or Alcore/Al2O3shell nanospheres is observed accompanied by a significant red shift in the extinction spectra at the parallel polarization direction of the incident light related to the dimer axis, while for the case of the perpendicular polarization direction, a weak plasmon coupling arises characterized by a slight blue shift in the extinction spectra. The electric field distribution profiles show that benefiting from the dielectric Al2O3 shell, the gap distance of Alcore/Al2O3shell nanosphere dimers can be tailored to 〈 1 nm scale and results in a very high electric field enhancement. The estimated surface-enhanced Raman scattering enhancement factors suggests that the Alcore/Al2O3shell nanosphere dimers with the gap of 〈 1 nm gave rise to an enhancement as high as 8.1 × 10^7 for interparticle gap = 0.5 nm. Our studies reveal that the Alcore/Al2O3shell nanosphere dimers may be promising substrates for surface-enhanced spectroscopy in the deep-ultraviolet region.展开更多
Gallium oxide(Ga_(2)O_(3))is a promising material for deep-ultraviolet(DUV)detection.In this work,Chlorin e6(Ce6)has been integrated with Ga_(2)O_(3)to achieve a DUV and visible dual-band photodetector,which can achie...Gallium oxide(Ga_(2)O_(3))is a promising material for deep-ultraviolet(DUV)detection.In this work,Chlorin e6(Ce6)has been integrated with Ga_(2)O_(3)to achieve a DUV and visible dual-band photodetector,which can achieve multiple target information and improve the recognition rate.The photodetector shows two separate response bands at 268 nm and 456 nm.The DUV response band has a responsivity of 9.63 A/W with a full width at half maximum(FWHM)of 54.5 nm;the visible response band has a responsivity of 1.17 A/W with an FWHM of 45.3 nm.This work may provide a simple way to design and fabricate photodetectors with dual-band response.展开更多
Deep-ultraviolet（DUV） light-emitting devices（LEDs） have a variety of potential applications.Zinc-oxide-based materials,which have wide bandgap and large exciton binding energy,have potential applications in high-p...Deep-ultraviolet（DUV） light-emitting devices（LEDs） have a variety of potential applications.Zinc-oxide-based materials,which have wide bandgap and large exciton binding energy,have potential applications in high-performance DUV LEDs.To realize such optoelectronic devices,the modulation of the bandgap is required.This has been demonstrated by the developments of Mg_xZn_（1-x）O and Be_xZn_（1-x）O alloys for the larger bandgap materials.Many efforts have been made to obtain DUV LEDs,and promising successes have been achieved continuously.In this article,we review the recent progress of and problems encountered in the research of ZnO-based DUV LEDs.展开更多
基金the National Natural Science Foundation of China(Grant No.62104085)the Innovation/Entrepreneurship Program of Jiangsu Province,China(Grant No.JSSCTD202146)。
文摘We investigate the polarization-induced doping in the gradient variation of Al composition in the pAl_(0.75)Ga_(0.25)N/Al_xGa_(1-x)N hole injection layer(HIL)for deep ultraviolet light-emitting diodes(DUV-LEDs)with an ultrathin p-GaN(4 nm)ohmic contact layer capable of emitting 277 nm.The experimental results show that the external quantum efficiency(EQE)and wall plug efficiency(WPE)of the structure graded from 0.75 to 0.55 in the HIL reach 5.49%and 5.04%,which are improved significantly by 182%and 209%,respectively,compared with the structure graded from 0.75 to 0.45,exhibiting a tremendous improvement.Both theoretical speculations and simulation results support that the larger the difference between 0.75 and x in the HIL,the higher the hole concentration that should be induced;thus,the DUV-LED has a higher internal quantum efficiency(IQE).Meanwhile,as the value of x decreases,the absorption of the DUV light emitted from the active region by the HIL is enhanced,reducing the light extraction efficiency(LEE).The IQE and LEE together affect the EQE performance of DUV-LEDs.To trade off the contradiction between the enhanced IQE and decreased LEE caused by the decrease in Al composition,the Al composition in the HIL was optimized through theoretical calculations and experiments.
基金the National Natural Science Foundation of China(Grant Nos.U22A2073,11974433,91833301,and 11974122)。
文摘We successfully fabricate a high performanceβ-phase(In_(0.09)Ga_(0.91))_(2)O_(3)single-crystalline film deep ultraviolet(DUV)solar-blind photodetector.The 2-inches high crystalline quality film is hetero-grown on the sapphire substrates using the plasma-assisted molecular beam epitaxy(PA-MBE).The smooth InGaO single crystalline film is used to construct the solar-blind DUV detector,which utilized an interdigitated Ti/Au electrode with a metal-semiconductor-metal structure.The device exhibits a low dark current of 40 pA(0 V),while its UV photon responsivity exceeds 450 A/W(50 V)at the peak wavelength of 232 nm with illumination intensity of 0.21 m W/cm^(2)and the UV/VIS rejection ratio(R232 nm/R380 nm)exceeds 4×10^(4).Furthermore,the devices demonstrate ultrafast transient characteristics for DUV signals,with fast-rising and fast-falling times of 80 ns and 420 ns,respectively.This excellent temporal dynamic behavior can be attributed to indium doping can adjust the electronic structure of Ga_(2)O_(3)alloys to enhance the performance of InGaO solar-blind detectors.Additionally,a two-dimensional DUV scanning image is captured using the InGaO photodetector as a sensor in an imaging system.Our results pave the way for future applications of two-dimensional array DUV photodetectors based on the large-scale InGaO heteroepitaxially grown alloy wide bandgap semiconductor films.
基金Supported by the Major State Basic Research Development Program of China(2011CB808300)the National Natural Science Foundation of China(11175240,11205234 and 11322550)
文摘Coherent light with orbital angular momentum(OAM)is of great interest.Recently,OAM light generation by coupling a relativistic electron beam with a Gaussian mode laser pulse at the high harmonics of a helical undulator has been demonstrated experimentally.In this paper,the possibility of delivering coherent OAM light at the 3^(rd)harmonic of the Gaussian mode seed laser is discussed for the Shanghai deep ultraviolet freeelectron laser(SDUV-FEL).Considerations are given on the experiment setup,the expected performance and the possible measurement method.
基金supported by the State Key Program for Basic Research of China (Grant No. 2010CB630706)National High Technology Research and Development Program of Chinathe National Natural Science Foundation of China (Grant No. 61138004)
文摘We develop a picosecond widely tunable laser in a deep-ultraviolet region from 175 nm to 210 nm, generated by two stages of frequency doubling of a 80-MHz mode-locked picosecond Ti：sapphire laser. A β-BaB2O4 walk-off compensation configuration and a KBe2BO3F2 prism-coupled device are adopted for the generation of second harmonic and fourth harmonics, respectively. The highest power is 3.72 mW at 193 nm, and the fluctuation at 2.85 mW in 130 rain is less than ±2%.
基金supported by the National Natural Science Foundation of China(Grant Nos.11104079 and 61378033)the National Key Scientific Instrument Project of China(Grant No.2012YQ150092)+1 种基金the Research Foundation for the Doctoral Program of Higher Education of China(Grant No.20110076120019)the State Key Laboratory of Luminescent Materials and Devices at South China University of Technology
文摘The localized surface plasmon resonance properties of Al and Alcore/Al2O3shell nanosphere dimers with Al and Al core nanosphere radii of 20 nm and Al2O3 shell of 2 nm in the deep-ultraviolet region have been studied using the finite difference time domain method. The extinction spectra and the electric field distribution profiles of the two dimers for various gap distances between two individual nanospheres are compared with those of the corresponding monomers to reveal the extent of plasmon coupling. It is found that with the interparticle distance decreasing, a strong plasmon coupling between two Al or Alcore/Al2O3shell nanospheres is observed accompanied by a significant red shift in the extinction spectra at the parallel polarization direction of the incident light related to the dimer axis, while for the case of the perpendicular polarization direction, a weak plasmon coupling arises characterized by a slight blue shift in the extinction spectra. The electric field distribution profiles show that benefiting from the dielectric Al2O3 shell, the gap distance of Alcore/Al2O3shell nanosphere dimers can be tailored to 〈 1 nm scale and results in a very high electric field enhancement. The estimated surface-enhanced Raman scattering enhancement factors suggests that the Alcore/Al2O3shell nanosphere dimers with the gap of 〈 1 nm gave rise to an enhancement as high as 8.1 × 10^7 for interparticle gap = 0.5 nm. Our studies reveal that the Alcore/Al2O3shell nanosphere dimers may be promising substrates for surface-enhanced spectroscopy in the deep-ultraviolet region.
文摘Gallium oxide(Ga_(2)O_(3))is a promising material for deep-ultraviolet(DUV)detection.In this work,Chlorin e6(Ce6)has been integrated with Ga_(2)O_(3)to achieve a DUV and visible dual-band photodetector,which can achieve multiple target information and improve the recognition rate.The photodetector shows two separate response bands at 268 nm and 456 nm.The DUV response band has a responsivity of 9.63 A/W with a full width at half maximum(FWHM)of 54.5 nm;the visible response band has a responsivity of 1.17 A/W with an FWHM of 45.3 nm.This work may provide a simple way to design and fabricate photodetectors with dual-band response.
基金Project supported by the National Natural Science Foundation for Distinguished Young Scholars of China(Grant No.61425021)the Natural Natural Science Foundation of China(Grant Nos.11374296,61376054,61475153,and 61604132)
文摘Deep-ultraviolet（DUV） light-emitting devices（LEDs） have a variety of potential applications.Zinc-oxide-based materials,which have wide bandgap and large exciton binding energy,have potential applications in high-performance DUV LEDs.To realize such optoelectronic devices,the modulation of the bandgap is required.This has been demonstrated by the developments of Mg_xZn_（1-x）O and Be_xZn_（1-x）O alloys for the larger bandgap materials.Many efforts have been made to obtain DUV LEDs,and promising successes have been achieved continuously.In this article,we review the recent progress of and problems encountered in the research of ZnO-based DUV LEDs.
文摘研制了千赫兹213 nm深紫外全固态激光器。激光器采用脉冲LD侧面泵浦方式和电光调Q技术,实现了10瓦级基频光的稳定输出。利用多次倍频技术,实现了稳定的213 nm深紫外激光输出。当LD泵浦电流为80 A时,213 nm激光输出的最大平均功率达到了151 m W,激光器重复频率为1 k Hz,激光脉冲宽度为10ns,功率不稳定度为3%。同时,对激光在非线性晶体中的偏振匹配和不同重复频率条件下的激光器运转特性进行了分析。
