The influence of the virtual guard ring width(GRW)on the performance of the p-well/deep n-well single-photon avalanche diode(SPAD)in a 180 nm standard CMOS process was investigated.TCAD simulation demonstrates that th...The influence of the virtual guard ring width(GRW)on the performance of the p-well/deep n-well single-photon avalanche diode(SPAD)in a 180 nm standard CMOS process was investigated.TCAD simulation demonstrates that the electric field strength and current density in the guard ring are obviously enhanced when GRW is decreased to 1μm.It is experimentally found that,compared with an SPAD with GRW=2μm,the dark count rate(DCR)and afterpulsing probability(AP)of the SPAD with GRW=1μm is significantly increased by 2.7 times and twofold,respectively,meanwhile,its photon detection probability(PDP)is saturated and hard to be promoted at over 2 V excess bias voltage.Although the fill factor(FF)can be enlarged by reducing GRW,the dark noise of devices is negatively affected due to the enhanced trap-assisted tunneling(TAT)effect in the 1μm guard ring region.By comparison,the SPAD with GRW=2μm can achieve a better trade-off between the FF and noise performance.Our study provides a design guideline for guard rings to realize a low-noise SPAD for large-array applications.展开更多
A gas detector 140×140×140 mm^(3)in size,termed the compact active target time projection chamber(CAT-TPC),was developed in this study to measure resonant scattering associated with cluster structures in uns...A gas detector 140×140×140 mm^(3)in size,termed the compact active target time projection chamber(CAT-TPC),was developed in this study to measure resonant scattering associated with cluster structures in unstable nuclei.The CAT-TPC consists of an electronic field cage,double-thick gas-electron-multiplier foils,a general-purpose digital data acquisition system,and a newly developed two-dimensional strip-readout structure.The CAT-TPC was operated using a^(4)He(96%)+CO_(2)(4%)gas mixture at 400 mbar.The working gas also serves as an active target for tracking charged particles.The overall performance of the CAT-TPC was evaluated using a collimated a-particle source.A time resolution of less than 20 ns and a position resolution of less than 0.2 mm were observed along the electron drift direction.Threedimensional images of incident trajectories and scattering events can be clearly reconstructed under an angular resolution of approximately 0.45 degree.展开更多
A 4H-SiC power MOSFET with specific on-resistance of 3.4 mΩ·cm^2 and breakdown voltage exceeding 1.5 kV is designed and fabricated.Numerical simulations are carried out to optimize the electric field strength in...A 4H-SiC power MOSFET with specific on-resistance of 3.4 mΩ·cm^2 and breakdown voltage exceeding 1.5 kV is designed and fabricated.Numerical simulations are carried out to optimize the electric field strength in gate oxide and at the surface of the semiconductor material in the edge termination region.Additional n-type implantation in JFET region is implemented to reduce the specific on-resistance.The typical leakage current is less than 1μA at VDS=1.4 kV.Drain–source current reaches 50 A at VDS=0.75 V and VGS=20 V corresponding to an on-resistance of 15 mΩ.The typical gate threshold voltage is 2.6 V.展开更多
This paper presents the design and fabrication of an effective, robust and process-tolerant floating guard ring termination on high voltage 4H-SiC PiN diodes. Different design factors were studied by numerical simulat...This paper presents the design and fabrication of an effective, robust and process-tolerant floating guard ring termination on high voltage 4H-SiC PiN diodes. Different design factors were studied by numerical simulations and evaluated by device fabrication and measurement. The device fabrication was based on a 12 μm thick drift layer with an N-type doping concentration of 8 × 10^15 cm^-3. P^＋ regions in the termination structure and anode layer were formed by multiple aluminum implantations. The fabricated devices present a highest breakdown voltage of 1.4 kV, which is higher than the simulated value. For the fabricated 15 diodes in one chip, all of them exceeded the breakdown voltage of 1 kV and six of them reached the desired breakdown value of 1.2 kV.展开更多
The design, fabrication, and electrical characteristics of the 4H-SiC JBS diode with a breakdown voltage higher than 10 kV are presented. 60 floating guard rings have been used in the fabrication. Numerical simulation...The design, fabrication, and electrical characteristics of the 4H-SiC JBS diode with a breakdown voltage higher than 10 kV are presented. 60 floating guard rings have been used in the fabrication. Numerical simulations have been performed to select the doping level and thickness of the drift layer and the effectiveness of the edge termination technique. The n-type epilayer is 100 μm in thickness with a doping of 6 × 10^14 cm^-3. The on-state voltage was 2.7 V at JF = 13 A/cm^2.展开更多
4H-SiC junction barrier Schottky（JBS）diodes with four kinds of design have been fabricated and characterized using two different processes in which one is fabricated by making the P-type ohmic contact of the anode i...4H-SiC junction barrier Schottky（JBS）diodes with four kinds of design have been fabricated and characterized using two different processes in which one is fabricated by making the P-type ohmic contact of the anode independently,and the other is processed by depositing a Schottky metal multi-layer on the whole anode.The reverse performances are compared to find the influences of these factors.The results show that JBS diodes with field guard rings have a lower reverse current density and a higher breakdown voltage,and with independent P-type ohmic contact manufacturing,the reverse performance of 4H-SiC JBS diodes can be improved effectively. Furthermore,the P-type ohmic contact is studied in this work.展开更多
With the critical charge reduced to generate a single event effect （SEE） and high working frequency for a nanometer integrated circuit, the single event effect （SET） becomes increasingly serious for high performan...With the critical charge reduced to generate a single event effect （SEE） and high working frequency for a nanometer integrated circuit, the single event effect （SET） becomes increasingly serious for high performance SOC and DSP chips. To analyze the radiation-hardened method of SET for the nanometer integrated circuit, the n＋ guard ring and p＋ guard ring have been adopted in the layout for a 65 nm commercial radiation-hardened standard cell library. The weakest driving capacity inverter cell was used to evaluate the single event transient （SET） pulse-width distribution. We employed a dual-lane measurement circuit to get more accurate SET＇s pulse- width. Six kinds of ions, which provide LETs of 12.5, 22.5, 32.5, 42, 63, and 79.5 MeV-cm2/mg, respectively, have been utilized to irradiate the SET test circuit in the Beijing Tandem Accelerator Nuclear Physics National Laboratory. The testing results reveal that the pulse-width of most SETs is shorter than 400 ps in the range of LETefr from 12.5 MeV.cm2/mg to 79.5 MeV-cm2/mg and the pulse-width presents saturation tendency when the effective linear energy transfer （LETeff value is larger than 40 MeV-cm2/mg. The test results also show that the hardened commercial standard cell＇s pulse-width concentrates on 33 to 264 ps, which decreases by 40% compared to the pulse-width of the 65 nm commercial unhardened standard cell.展开更多
Purpose Segmented high purity germanium(HPGe)detectors have been used in many experiments to measure the position and energy deposition of gamma ray interactions.Significant efforts have been made to optimize the desig...Purpose Segmented high purity germanium(HPGe)detectors have been used in many experiments to measure the position and energy deposition of gamma ray interactions.Significant efforts have been made to optimize the design and simplify the fabrication process.Amorphous germanium(aGe)coating is a desirable method to realize blocking contact and facilitate the segmentation.Method In this study,a prototype segmented planar HPGe detector is fabricated using a wraparound lithium diffusion electrode for bias voltage applying and reliable mechanical mounting.A low leakage current design is realized based on conventional chemical polishing and aGe blocking.A guard ring(GR)is used to protect the metal strip electrodes within it from the surface leakage current.The GR and strip electrodes are coated onto the aGe layer.A multichannel charge sensitive preamplifier is connected to the strip electrodes,and the signal waveforms are digitized using a multichannel 100 MS/s analog-to-digital converter.Results and conclusion The charge collection time and amplitude are analyzed.An average energy resolution of 2 keV(full width at half maximum,FWHM)is realized at 662 keV.Charge collection is simulated via a Monte Carlo program.The spatial resolution is also estimated using the program.The front-end response and measured noise level are considered.According to the simulation results,sub-millimeter(FWHM at 122 keV)resolution can be achieved at the current noise level.展开更多
基金supported by the Jiangsu Agricultural Science and Technology Innovation Fund of China(No.CX(21)3062)the National Natural Science Foundation of China(No.62171233).
文摘The influence of the virtual guard ring width(GRW)on the performance of the p-well/deep n-well single-photon avalanche diode(SPAD)in a 180 nm standard CMOS process was investigated.TCAD simulation demonstrates that the electric field strength and current density in the guard ring are obviously enhanced when GRW is decreased to 1μm.It is experimentally found that,compared with an SPAD with GRW=2μm,the dark count rate(DCR)and afterpulsing probability(AP)of the SPAD with GRW=1μm is significantly increased by 2.7 times and twofold,respectively,meanwhile,its photon detection probability(PDP)is saturated and hard to be promoted at over 2 V excess bias voltage.Although the fill factor(FF)can be enlarged by reducing GRW,the dark noise of devices is negatively affected due to the enhanced trap-assisted tunneling(TAT)effect in the 1μm guard ring region.By comparison,the SPAD with GRW=2μm can achieve a better trade-off between the FF and noise performance.Our study provides a design guideline for guard rings to realize a low-noise SPAD for large-array applications.
基金supported by the National Key R&D Program of China(No.2018YFA0404403)the National Natural Science Foundation of China(Nos.U1967201,11875074,11875073,and 11961141003)the State Key Laboratory of Nuclear Physics and Technology,PKU(No.NPT2020KFY06)。
文摘A gas detector 140×140×140 mm^(3)in size,termed the compact active target time projection chamber(CAT-TPC),was developed in this study to measure resonant scattering associated with cluster structures in unstable nuclei.The CAT-TPC consists of an electronic field cage,double-thick gas-electron-multiplier foils,a general-purpose digital data acquisition system,and a newly developed two-dimensional strip-readout structure.The CAT-TPC was operated using a^(4)He(96%)+CO_(2)(4%)gas mixture at 400 mbar.The working gas also serves as an active target for tracking charged particles.The overall performance of the CAT-TPC was evaluated using a collimated a-particle source.A time resolution of less than 20 ns and a position resolution of less than 0.2 mm were observed along the electron drift direction.Threedimensional images of incident trajectories and scattering events can be clearly reconstructed under an angular resolution of approximately 0.45 degree.
基金supported by the National Science and Technology Major Project(No.2017YFB0102302)。
文摘A 4H-SiC power MOSFET with specific on-resistance of 3.4 mΩ·cm^2 and breakdown voltage exceeding 1.5 kV is designed and fabricated.Numerical simulations are carried out to optimize the electric field strength in gate oxide and at the surface of the semiconductor material in the edge termination region.Additional n-type implantation in JFET region is implemented to reduce the specific on-resistance.The typical leakage current is less than 1μA at VDS=1.4 kV.Drain–source current reaches 50 A at VDS=0.75 V and VGS=20 V corresponding to an on-resistance of 15 mΩ.The typical gate threshold voltage is 2.6 V.
基金supported by the National High Technology Research and Development Program of China(No.2011AA050401)the Project of State Grid Corporation of China(No.SGRIDGKJ[2013]210)
文摘This paper presents the design and fabrication of an effective, robust and process-tolerant floating guard ring termination on high voltage 4H-SiC PiN diodes. Different design factors were studied by numerical simulations and evaluated by device fabrication and measurement. The device fabrication was based on a 12 μm thick drift layer with an N-type doping concentration of 8 × 10^15 cm^-3. P^＋ regions in the termination structure and anode layer were formed by multiple aluminum implantations. The fabricated devices present a highest breakdown voltage of 1.4 kV, which is higher than the simulated value. For the fabricated 15 diodes in one chip, all of them exceeded the breakdown voltage of 1 kV and six of them reached the desired breakdown value of 1.2 kV.
文摘The design, fabrication, and electrical characteristics of the 4H-SiC JBS diode with a breakdown voltage higher than 10 kV are presented. 60 floating guard rings have been used in the fabrication. Numerical simulations have been performed to select the doping level and thickness of the drift layer and the effectiveness of the edge termination technique. The n-type epilayer is 100 μm in thickness with a doping of 6 × 10^14 cm^-3. The on-state voltage was 2.7 V at JF = 13 A/cm^2.
基金project supported by the National Natural Science Foundation of China(No61006060)the 13115 Innovation Engineering of Shannxi Province,China(No2008ZDKG-30)
文摘4H-SiC junction barrier Schottky（JBS）diodes with four kinds of design have been fabricated and characterized using two different processes in which one is fabricated by making the P-type ohmic contact of the anode independently,and the other is processed by depositing a Schottky metal multi-layer on the whole anode.The reverse performances are compared to find the influences of these factors.The results show that JBS diodes with field guard rings have a lower reverse current density and a higher breakdown voltage,and with independent P-type ohmic contact manufacturing,the reverse performance of 4H-SiC JBS diodes can be improved effectively. Furthermore,the P-type ohmic contact is studied in this work.
文摘With the critical charge reduced to generate a single event effect （SEE） and high working frequency for a nanometer integrated circuit, the single event effect （SET） becomes increasingly serious for high performance SOC and DSP chips. To analyze the radiation-hardened method of SET for the nanometer integrated circuit, the n＋ guard ring and p＋ guard ring have been adopted in the layout for a 65 nm commercial radiation-hardened standard cell library. The weakest driving capacity inverter cell was used to evaluate the single event transient （SET） pulse-width distribution. We employed a dual-lane measurement circuit to get more accurate SET＇s pulse- width. Six kinds of ions, which provide LETs of 12.5, 22.5, 32.5, 42, 63, and 79.5 MeV-cm2/mg, respectively, have been utilized to irradiate the SET test circuit in the Beijing Tandem Accelerator Nuclear Physics National Laboratory. The testing results reveal that the pulse-width of most SETs is shorter than 400 ps in the range of LETefr from 12.5 MeV.cm2/mg to 79.5 MeV-cm2/mg and the pulse-width presents saturation tendency when the effective linear energy transfer （LETeff value is larger than 40 MeV-cm2/mg. The test results also show that the hardened commercial standard cell＇s pulse-width concentrates on 33 to 264 ps, which decreases by 40% compared to the pulse-width of the 65 nm commercial unhardened standard cell.
基金supported by the National Natural Science Foundation of China(Grant No.U1865205).
文摘Purpose Segmented high purity germanium(HPGe)detectors have been used in many experiments to measure the position and energy deposition of gamma ray interactions.Significant efforts have been made to optimize the design and simplify the fabrication process.Amorphous germanium(aGe)coating is a desirable method to realize blocking contact and facilitate the segmentation.Method In this study,a prototype segmented planar HPGe detector is fabricated using a wraparound lithium diffusion electrode for bias voltage applying and reliable mechanical mounting.A low leakage current design is realized based on conventional chemical polishing and aGe blocking.A guard ring(GR)is used to protect the metal strip electrodes within it from the surface leakage current.The GR and strip electrodes are coated onto the aGe layer.A multichannel charge sensitive preamplifier is connected to the strip electrodes,and the signal waveforms are digitized using a multichannel 100 MS/s analog-to-digital converter.Results and conclusion The charge collection time and amplitude are analyzed.An average energy resolution of 2 keV(full width at half maximum,FWHM)is realized at 662 keV.Charge collection is simulated via a Monte Carlo program.The spatial resolution is also estimated using the program.The front-end response and measured noise level are considered.According to the simulation results,sub-millimeter(FWHM at 122 keV)resolution can be achieved at the current noise level.
