In this study,the mechanism and characteristics of the responseαparticles and the damage caused by them in CMOS active pixel(APS)sensors were investigated.A detection and compensation algorithm for dead pixels caused...In this study,the mechanism and characteristics of the responseαparticles and the damage caused by them in CMOS active pixel(APS)sensors were investigated.A detection and compensation algorithm for dead pixels caused byαparticle ionizing radiation was proposed,and the effects of dead-pixel compensation algorithms were compared and analyzed under different parameter conditions.The experimental results show thatαparticle response signal has highest accuracy at 9 dB gain,with an obvious“target-ring”distribution.With increasing cumulative dose,the CMOS APS pedestal tends to saturation while dead pixels continue increasing.Though some pixel damage recovers through natural annealing,the dead-to-noise ratio increases with irradiation time,reaching 32.54%after 72 h.A hierarchical clustering dead-pixel detection method is proposed,categorizing pixels into two types:those within and outside the response event.A classification compensation strategy combining mean and majority filtering is proposed.This compensation algorithm can address dead-pixel interference without affectingαparticle radiation response data.When iterated multiple times and with integration time exceeding 6.31 ms,the number of dead pixels can be effectively reduced.展开更多
针对传统4H-SiCα粒子探测器金属电极“死层”较厚导致能量分辨率受限的问题,本文采用单原子层厚石墨烯作为肖特基接触电极及入射窗,以抑制“死层”效应.SRIM(stopping and range of ions in matter)模拟显示,100 nm厚Ni,Au电极对241Am...针对传统4H-SiCα粒子探测器金属电极“死层”较厚导致能量分辨率受限的问题,本文采用单原子层厚石墨烯作为肖特基接触电极及入射窗,以抑制“死层”效应.SRIM(stopping and range of ions in matter)模拟显示,100 nm厚Ni,Au电极对241Amα粒子的垂直入射能损分别约为38.36 keV,43.50 keV,且能损随入射角增大显著上升,而石墨烯电极能损始终低于0.04 keV.Geant4模拟进一步显示,当α粒子在0—π/3圆锥半角立体角均匀入射时,Ni,Au电极“死层”对能量分辨率的贡献分别为0.37%和0.46%,约占4H-SiCα探测器典型能量分辨率(~1%)的37%,46%,而石墨烯电极的贡献仅占0.03%,证实其可显著降低“死层”引起的能损及峰展宽.采用PMMA辅助湿法转移工艺将石墨烯转移至4H-SiC表面,构建探测器原理样机.拉曼光谱证实石墨烯成功转移至4H-SiC外延表面;器件表现出优良的整流特性及较低的漏电流;在241Am辐照下获得清晰的α能谱峰,空气中能量分辨率约为4.64%.实验验证了石墨烯可作为4H-SiC肖特基电极应用于α粒子探测.本工作为后续研制高能量分辨率石墨烯/4H-SiCα探测器奠定了基础.展开更多
Zinc substitution in Cd1−xZnxTe(CZT)alloys emerges as a powerful strategy for engineering their structural,elastic,mechanical,acoustic and thermal properties,thereby enhancing their potential for high-performanc...Zinc substitution in Cd1−xZnxTe(CZT)alloys emerges as a powerful strategy for engineering their structural,elastic,mechanical,acoustic and thermal properties,thereby enhancing their potential for high-performance optoelectronic and radiation detection applications.In this work,a comprehensive first-principles investigation based onDensity Functional Theory,within both theGeneralizedGradientApproximation and the LocalDensityApproximation,is conducted to systematically explore the composition-dependent behavior of CZT across the full concentration range(0≤×≤1)in the cubic zinc-blende phase.The calculated elastic constants satisfy the Born stability criteria for all compositions,confirming the intrinsic mechanical stability of the alloys upon Zn incorporation.A pronounced and continuous increase in the bulk modulus,shear modulus and Young modulus is observed with increasing Zn content,revealing a significant enhancement in lattice rigidity driven by the formation of shorter,stronger Zn-Te bonds and improved bond covalency.Despite this stiffening,CZT alloys consistently exhibit ductile behavior,as demonstrated by positive Cauchy pressures,Pugh ratios well above the critical value for ductility(B/G>1.75),and Poisson ratios within the range of 0.29-0.37,indicating a favorable balance between strength and deformability.The Vickers hardness shows a systematic increase from 1.89 to 6.66 GPa with Zn concentration,highlighting improved resistance to plastic deformation while maintaining the moderate hardness typical of Ⅱ-Ⅵ semiconductors.Additionally,the moderate elastic anisotropy indicates controlled directional dependence without compromising structural integrity.Concurrently,the monotonic enhancement of the longitudinal,transverse and average sound velocities reflects increasingly efficient elastic wave propagation and improved lattice cohesion.The Debye temperature rises significantly from approximately 163 to 227 K,providing strong evidence of reinforced interatomic bonding and superior thermal stability.Collectively,these results deliver a coherent and in-depth theoretical framework demonstrating that the physical properties of CZT alloys can be precisely tuned through compositional engineering.This tunability,combined with their inherent stability and balanced mechanical performance,positions CZT as a highly promising and versatile material platform.It is well suited for next-generation radiation detectors and advanced semiconductor devices operating,even under demanding mechanical and thermal conditions.展开更多
We developed a dedicated data analysis framework for silicon strip detector telescopes(SSDTs)of the Compact Spectrometer for Heavy-IoN Experiments(CSHINE)that addresses the challenges of processing complex signals.The...We developed a dedicated data analysis framework for silicon strip detector telescopes(SSDTs)of the Compact Spectrometer for Heavy-IoN Experiments(CSHINE)that addresses the challenges of processing complex signals.The framework integrates advanced algorithms for precise calibration,accurate particle identification,and efficient event reconstruction,aiming to account for critical experimental factors such as charge-sharing effects,multi-hit event resolution,and detector response nonuniformity.Its robust performance was demonstrated through the successful analysis of light-charged particles in the 25 MeV/u86Kr+124Sn experiment conducted at the first Radioactive Ion Beam Line in Lanzhou,allowing for precise extraction of physical observables,including energy,momentum,and particle type.Furthermore,utilizing the reconstructed physical information,such as the number of effective physical events and energy spectra to optimize the track recognition algorithm,the final track recognition efficiencies of approximately 90%were achieved.This framework establishes a valuable reference methodology for SSDT-based detector systems in heavy-ion reaction experiments,thereby significantly enhancing the accuracy and efficiency of data analysis in nuclear physics research.展开更多
Cadmium telluride(CdTe),which has a high average atomic number and a unique band structure,is a leading material for room-temperature X/γ-ray detectors.Resistivity and mobility are the two most important properties o...Cadmium telluride(CdTe),which has a high average atomic number and a unique band structure,is a leading material for room-temperature X/γ-ray detectors.Resistivity and mobility are the two most important properties of detector-grade CdTe single crystals.However,despite decades of research,the fabrication of high-resistivity and high-mobility CdTe single crystals faces persistent challenges,primarily because the stoichiometric composition cannot be well controlled owing to the high volatility of Cd under high-temperature conditions.This volatility introduces Te inclusions and cadmium vacancies(VCd)into the as-grown CdTe ingot,which significantly degrades the device performance.In this study,we successfully obtained detector-grade CdTe single crystals by simultaneously employing a Cd reservoir and chlorine(Cl)dopants via a vertical gradient freeze(VGF)method.By installing a Cd reservoir,we can maintain the Cd pressure under the crystal growth conditions,thereby preventing the accumulation of Te in the CdTe ingot.Additionally,the existence of the Cl dopant helps improve the CdTe resistivity by minimizing VCddensity through the formation of an acceptor complex(ClTe-VCd)-1.The crystalline quality of the obtained CdTe(Cl)was evidenced by a reduction in large Te inclusions,high optical transmission(60%),and a sharp absorption edge(1.456 eV).The presence of substitutional Cl dopants,known as ClTe+,simultaneously supports the record high resistivity of 1.5×1010Ω·cm and remarkable electron mobility of 1075±88 cm2V-1s-1simultaneously,has been confirmed by photoluminescence spectroscopy.Moreover,using our crystals,we fabricated a planar detector withμτeof(1.11±0.04)×10-4cm2∕V,which performed with a decent radiation-detection feature.This study demonstrates that the vapor-pressure-controlled VGF method is a viable technical route for fabricating detector-grade CdTe crystals.展开更多
基金supported by the National Natural Science Foundation of China(No.11905102)Hunan Provincial Postgraduate Research and Innovation Project(No.QL20230234)。
摘要In this study,the mechanism and characteristics of the responseαparticles and the damage caused by them in CMOS active pixel(APS)sensors were investigated.A detection and compensation algorithm for dead pixels caused byαparticle ionizing radiation was proposed,and the effects of dead-pixel compensation algorithms were compared and analyzed under different parameter conditions.The experimental results show thatαparticle response signal has highest accuracy at 9 dB gain,with an obvious“target-ring”distribution.With increasing cumulative dose,the CMOS APS pedestal tends to saturation while dead pixels continue increasing.Though some pixel damage recovers through natural annealing,the dead-to-noise ratio increases with irradiation time,reaching 32.54%after 72 h.A hierarchical clustering dead-pixel detection method is proposed,categorizing pixels into two types:those within and outside the response event.A classification compensation strategy combining mean and majority filtering is proposed.This compensation algorithm can address dead-pixel interference without affectingαparticle radiation response data.When iterated multiple times and with integration time exceeding 6.31 ms,the number of dead pixels can be effectively reduced.
摘要针对传统4H-SiCα粒子探测器金属电极“死层”较厚导致能量分辨率受限的问题,本文采用单原子层厚石墨烯作为肖特基接触电极及入射窗,以抑制“死层”效应.SRIM(stopping and range of ions in matter)模拟显示,100 nm厚Ni,Au电极对241Amα粒子的垂直入射能损分别约为38.36 keV,43.50 keV,且能损随入射角增大显著上升,而石墨烯电极能损始终低于0.04 keV.Geant4模拟进一步显示,当α粒子在0—π/3圆锥半角立体角均匀入射时,Ni,Au电极“死层”对能量分辨率的贡献分别为0.37%和0.46%,约占4H-SiCα探测器典型能量分辨率(~1%)的37%,46%,而石墨烯电极的贡献仅占0.03%,证实其可显著降低“死层”引起的能损及峰展宽.采用PMMA辅助湿法转移工艺将石墨烯转移至4H-SiC表面,构建探测器原理样机.拉曼光谱证实石墨烯成功转移至4H-SiC外延表面;器件表现出优良的整流特性及较低的漏电流;在241Am辐照下获得清晰的α能谱峰,空气中能量分辨率约为4.64%.实验验证了石墨烯可作为4H-SiC肖特基电极应用于α粒子探测.本工作为后续研制高能量分辨率石墨烯/4H-SiCα探测器奠定了基础.
摘要Zinc substitution in Cd1−xZnxTe(CZT)alloys emerges as a powerful strategy for engineering their structural,elastic,mechanical,acoustic and thermal properties,thereby enhancing their potential for high-performance optoelectronic and radiation detection applications.In this work,a comprehensive first-principles investigation based onDensity Functional Theory,within both theGeneralizedGradientApproximation and the LocalDensityApproximation,is conducted to systematically explore the composition-dependent behavior of CZT across the full concentration range(0≤×≤1)in the cubic zinc-blende phase.The calculated elastic constants satisfy the Born stability criteria for all compositions,confirming the intrinsic mechanical stability of the alloys upon Zn incorporation.A pronounced and continuous increase in the bulk modulus,shear modulus and Young modulus is observed with increasing Zn content,revealing a significant enhancement in lattice rigidity driven by the formation of shorter,stronger Zn-Te bonds and improved bond covalency.Despite this stiffening,CZT alloys consistently exhibit ductile behavior,as demonstrated by positive Cauchy pressures,Pugh ratios well above the critical value for ductility(B/G>1.75),and Poisson ratios within the range of 0.29-0.37,indicating a favorable balance between strength and deformability.The Vickers hardness shows a systematic increase from 1.89 to 6.66 GPa with Zn concentration,highlighting improved resistance to plastic deformation while maintaining the moderate hardness typical of Ⅱ-Ⅵ semiconductors.Additionally,the moderate elastic anisotropy indicates controlled directional dependence without compromising structural integrity.Concurrently,the monotonic enhancement of the longitudinal,transverse and average sound velocities reflects increasingly efficient elastic wave propagation and improved lattice cohesion.The Debye temperature rises significantly from approximately 163 to 227 K,providing strong evidence of reinforced interatomic bonding and superior thermal stability.Collectively,these results deliver a coherent and in-depth theoretical framework demonstrating that the physical properties of CZT alloys can be precisely tuned through compositional engineering.This tunability,combined with their inherent stability and balanced mechanical performance,positions CZT as a highly promising and versatile material platform.It is well suited for next-generation radiation detectors and advanced semiconductor devices operating,even under demanding mechanical and thermal conditions.
基金supported by the National Natural Science Foundation of China(NNSFC)(Nos.12375123,12205160,and 12335008)the Natural Science Foundation of Henan Province,China(No.242300421048)the postgraduate research and practice innovation project of Henan Normal University(No.YB202402).
摘要We developed a dedicated data analysis framework for silicon strip detector telescopes(SSDTs)of the Compact Spectrometer for Heavy-IoN Experiments(CSHINE)that addresses the challenges of processing complex signals.The framework integrates advanced algorithms for precise calibration,accurate particle identification,and efficient event reconstruction,aiming to account for critical experimental factors such as charge-sharing effects,multi-hit event resolution,and detector response nonuniformity.Its robust performance was demonstrated through the successful analysis of light-charged particles in the 25 MeV/u86Kr+124Sn experiment conducted at the first Radioactive Ion Beam Line in Lanzhou,allowing for precise extraction of physical observables,including energy,momentum,and particle type.Furthermore,utilizing the reconstructed physical information,such as the number of effective physical events and energy spectra to optimize the track recognition algorithm,the final track recognition efficiencies of approximately 90%were achieved.This framework establishes a valuable reference methodology for SSDT-based detector systems in heavy-ion reaction experiments,thereby significantly enhancing the accuracy and efficiency of data analysis in nuclear physics research.
基金supported by the National Key R&D Program(Nos.2023YFE0108500 and 2023YFF0719500)the National Natural Science Foundation of China(Nos.52072300 and 52302199)+2 种基金the Guangdong Basic and Applied Basic Research Foundation(No.2022A1515110538)Key Research and Development Program of Shaanxi(No.2023-GHZD-48)the Fundamental Research Funds for the Central Universities.
摘要Cadmium telluride(CdTe),which has a high average atomic number and a unique band structure,is a leading material for room-temperature X/γ-ray detectors.Resistivity and mobility are the two most important properties of detector-grade CdTe single crystals.However,despite decades of research,the fabrication of high-resistivity and high-mobility CdTe single crystals faces persistent challenges,primarily because the stoichiometric composition cannot be well controlled owing to the high volatility of Cd under high-temperature conditions.This volatility introduces Te inclusions and cadmium vacancies(VCd)into the as-grown CdTe ingot,which significantly degrades the device performance.In this study,we successfully obtained detector-grade CdTe single crystals by simultaneously employing a Cd reservoir and chlorine(Cl)dopants via a vertical gradient freeze(VGF)method.By installing a Cd reservoir,we can maintain the Cd pressure under the crystal growth conditions,thereby preventing the accumulation of Te in the CdTe ingot.Additionally,the existence of the Cl dopant helps improve the CdTe resistivity by minimizing VCddensity through the formation of an acceptor complex(ClTe-VCd)-1.The crystalline quality of the obtained CdTe(Cl)was evidenced by a reduction in large Te inclusions,high optical transmission(60%),and a sharp absorption edge(1.456 eV).The presence of substitutional Cl dopants,known as ClTe+,simultaneously supports the record high resistivity of 1.5×1010Ω·cm and remarkable electron mobility of 1075±88 cm2V-1s-1simultaneously,has been confirmed by photoluminescence spectroscopy.Moreover,using our crystals,we fabricated a planar detector withμτeof(1.11±0.04)×10-4cm2∕V,which performed with a decent radiation-detection feature.This study demonstrates that the vapor-pressure-controlled VGF method is a viable technical route for fabricating detector-grade CdTe crystals.