Radiation doses to patients in diagnostics and interventional radiology need to be optimized to comply with the principles of radiation protection in medical practice. This involves using specific detectors with respe...Radiation doses to patients in diagnostics and interventional radiology need to be optimized to comply with the principles of radiation protection in medical practice. This involves using specific detectors with respective diagnostic beams to carry out quality control/quality assurance tests needed to optimize patient doses in the hospital. Semiconductor detectors are used in dosimetry to verify the equipment performance and dose to patients. This work aims to assess the performance, energy dependence, and response of five commercially available semiconductor detectors in RQR, RQR-M, RQA, and RQT at Secondary Standard Dosimetry for clinical applications. The diagnostic beams were generated using Exradin A4 reference ion chamber and PTW electrometer. The ambient temperature and pressure were noted for KTP correction. The detectors designed for RQR showed good performance in RQT beams and vice versa. The detectors designed for RQR-M displayed high energy dependency in other diagnostic beams. The type of diagnostic beam quality determines the response of semiconductor detectors. Therefore, a detector should be calibrated according to the beam qualities to be measured.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(V_(Cd))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 V_(Cd)density through the formation of an acceptor complex(Cl_(Te)-V_(Cd))^(-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 Cl_(Te)^(+),simultaneously supports the record high resistivity of 1.5×10^(10)Ω·cm and remarkable electron mobility of 1075±88 cm^(2)V^(-1)s^(-1)simultaneously,has been confirmed by photoluminescence spectroscopy.Moreover,using our crystals,we fabricated a planar detector withμτ_(e)of(1.11±0.04)×10^(-4)cm^(2)∕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
Purpose Development of highly sensitive semiconductor detectors of large diameter and manufacturing of a measuring complex—a radiometer based on the developed detectors for studying the activity of alpha particles an...Purpose Development of highly sensitive semiconductor detectors of large diameter and manufacturing of a measuring complex—a radiometer based on the developed detectors for studying the activity of alpha particles and the volumetric activity of radon in various media.Methods The detectors were manufactured using surface-barrier and heterojunction technologies.Polishing etchant formulations for silicon have been developed.To obtain plane-parallelism of the plates during chemical etching,a special dynamic setup was used.The structure of the radiometer,electrical circuits,and device software have been developed.Results The results of the development of technology for the manufacture of detectors of large dimensions(30-100 mm in diameter)are presented.Studies of the electrical and radiometric characteristics of surface-barrier n detectors and detectors based on Al-αGe-pSi-Au heterojunctions were carried out.The principle of operation of the electronic components of a radiometer made using these detectors is also given.Conclusion The data of monitoring of radon content in soil air are given.Monitoring results showed that the concentration varies depending on temperature,humidity,and time of day.The GSM/SMS module allows the device to operate in real time.展开更多
Topmetal-M2 is a large-area pixel sensor chip fabricated using the GSMC 130 nm CMOS process in 2021.The pixel array of Topmetal-M2 consists of pixels of 400 rows×512 columns with a pixel pitch of 45μm×45μm...Topmetal-M2 is a large-area pixel sensor chip fabricated using the GSMC 130 nm CMOS process in 2021.The pixel array of Topmetal-M2 consists of pixels of 400 rows×512 columns with a pixel pitch of 45μm×45μm.The array is divided into 16 subarrays,with pixels of 400 rows×32 columns per subarray.Each pixel incorporates two charge sensors:a diode sensor and a Topmetal sensor.The in-pixel circuit primarily consists of a charge-sensitive amplifier for energy measurements,a discriminator with a peak-holding circuit,and a time-to-amplitude converter for time-of-arrival measurements.The pixel of Topmetal-M2 has a charge input range of~0-3 k e-,a voltage output range of~0-180 mV,and a charge-voltage conversion gain of~59.56μV∕e-.The average equivalent noise charge of Topmetal-M2,which includes the readout electronic system noise,is~43.45 e-.In the scanning mode,the time resolution of Topmetal-M2 is 1 LSB=1.25μs,and the precision is^()7.41μs.At an operating voltage of 1.5 V,Topmetal-M2 has a power consumption of~49 mW∕cm~2.In this article,we provide a comprehensive overview of the chip architecture,pixel working principles,and functional behavior of Topmetal-M2.Furthermore,we present the results of preliminary tests conducted on Topmetal-M2,namely,alpha-particle and soft X-ray tests.展开更多
A chemical vapour deposition （CVD） diamond film detector was prepared and the main characteristics for pulsed proton detection were studied at Beijing Tandem Accelerator. The result shows that the charge collection ...A chemical vapour deposition （CVD） diamond film detector was prepared and the main characteristics for pulsed proton detection were studied at Beijing Tandem Accelerator. The result shows that the charge collection efficiency of the detector increases with increasing electric field intensity and reaches to 9.44% at 5 V/μm with the charge collection distance of 15.9 μm. The relationship between the sensitivity of the detector and proton energy is consistent with the Monte Carlo （MC） simulation result. Its plasma time for a pulse with 4.85×10^5 protons is 1l.2ns. The dose threshold for onset of damage under 9MeV proton irradiation in the detector is about 10^13 cm^-2. All of the results show that a CVD diamond detector has fast time response and high radiation hardness, and can be used in pulsed proton detection.展开更多
针对传统α能谱测量系统存在的本底噪声高、能量分辨率受限等问题,研制了基于FPGA技术的数字多道分析模块与PIPS半导体探测器相结合的新一代α能谱测量系统。该系统设计基于FPGA的多参数数字多道处理架构,利用硬件描述语言实现高速脉冲...针对传统α能谱测量系统存在的本底噪声高、能量分辨率受限等问题,研制了基于FPGA技术的数字多道分析模块与PIPS半导体探测器相结合的新一代α能谱测量系统。该系统设计基于FPGA的多参数数字多道处理架构,利用硬件描述语言实现高速脉冲幅度提取算法,开发了自适应基线恢复技术和波形动态甄别机制。实验数据表明,该系统能量分辨率最低可达到16.293 ke V@5.486 MeV(FWHM),支持8192道能谱分析,具备多探测器同步采集能力,为环境放射性监测、核安全保障、食品安全等领域的超低水平α核素分析提供了可靠的技术手段。展开更多
Microstructure of P + Si 0.65 Ge 0.35 /p Si HIP infrared detector has been studied by using localization cross section transmission electron microscopy. The photosensitive region of the detector consists of 6 P + Si 0...Microstructure of P + Si 0.65 Ge 0.35 /p Si HIP infrared detector has been studied by using localization cross section transmission electron microscopy. The photosensitive region of the detector consists of 6 P + Si 0.65 Ge 0.35 layers and 5 UD Si layers, which are flat and have thickness of 6 nm and 32 nm, respectively. A stress field exists on the interface between Si 0.65 Ge 0.35 and UD Si layers, but no any crystal defect has been found in this region, except the edges of this region. Both Si 0.65 Ge 0.35 and UD Si layers on amorphous SiO 2 layer consist of polycrystals and are in wave. There is defect area in the edges of photosensitive region. The area appears in a shape of inverse triangle and the maximum width is less than 120 nm. The crystal defects are stacking faults and microtwins.展开更多
In recent years, the narrow bandgap antimonide based compound semiconductors (ABCS) are widely regarded as the first candidate materials for fabrication of the third generation infrared photon detectors and integrated...In recent years, the narrow bandgap antimonide based compound semiconductors (ABCS) are widely regarded as the first candidate materials for fabrication of the third generation infrared photon detectors and integrated circuits with ultra-high speed and ultra-low power consumption. Due to their unique bandgap structure and physical properties, it makes a vast space to develop various novel devices, and becomes a hot research area in many developed countries such as USA, Japan, Germany and Israel etc. Research progress in the preparation and application of ABCS materials, existing problems and some latest results are briefly introduced.展开更多
文摘Radiation doses to patients in diagnostics and interventional radiology need to be optimized to comply with the principles of radiation protection in medical practice. This involves using specific detectors with respective diagnostic beams to carry out quality control/quality assurance tests needed to optimize patient doses in the hospital. Semiconductor detectors are used in dosimetry to verify the equipment performance and dose to patients. This work aims to assess the performance, energy dependence, and response of five commercially available semiconductor detectors in RQR, RQR-M, RQA, and RQT at Secondary Standard Dosimetry for clinical applications. The diagnostic beams were generated using Exradin A4 reference ion chamber and PTW electrometer. The ambient temperature and pressure were noted for KTP correction. The detectors designed for RQR showed good performance in RQT beams and vice versa. The detectors designed for RQR-M displayed high energy dependency in other diagnostic beams. The type of diagnostic beam quality determines the response of semiconductor detectors. Therefore, a detector should be calibrated according to the beam qualities to be measured.
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.
文摘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(V_(Cd))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 V_(Cd)density through the formation of an acceptor complex(Cl_(Te)-V_(Cd))^(-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 Cl_(Te)^(+),simultaneously supports the record high resistivity of 1.5×10^(10)Ω·cm and remarkable electron mobility of 1075±88 cm^(2)V^(-1)s^(-1)simultaneously,has been confirmed by photoluminescence spectroscopy.Moreover,using our crystals,we fabricated a planar detector withμτ_(e)of(1.11±0.04)×10^(-4)cm^(2)∕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.
基金This work was financially supported by the Fundamental Research Programs of the Uzbekistan Academy of Sciences on the topic“Development and investigation of electrophysical and radiometric characteristics of large-sized ionizing radiation detectors”.
文摘Purpose Development of highly sensitive semiconductor detectors of large diameter and manufacturing of a measuring complex—a radiometer based on the developed detectors for studying the activity of alpha particles and the volumetric activity of radon in various media.Methods The detectors were manufactured using surface-barrier and heterojunction technologies.Polishing etchant formulations for silicon have been developed.To obtain plane-parallelism of the plates during chemical etching,a special dynamic setup was used.The structure of the radiometer,electrical circuits,and device software have been developed.Results The results of the development of technology for the manufacture of detectors of large dimensions(30-100 mm in diameter)are presented.Studies of the electrical and radiometric characteristics of surface-barrier n detectors and detectors based on Al-αGe-pSi-Au heterojunctions were carried out.The principle of operation of the electronic components of a radiometer made using these detectors is also given.Conclusion The data of monitoring of radon content in soil air are given.Monitoring results showed that the concentration varies depending on temperature,humidity,and time of day.The GSM/SMS module allows the device to operate in real time.
基金supported by the National Key Research and Development Program of China(No.2020YFE0202002)the National Natural Science Foundation of China(Nos.11875146 and U1932143)。
文摘Topmetal-M2 is a large-area pixel sensor chip fabricated using the GSMC 130 nm CMOS process in 2021.The pixel array of Topmetal-M2 consists of pixels of 400 rows×512 columns with a pixel pitch of 45μm×45μm.The array is divided into 16 subarrays,with pixels of 400 rows×32 columns per subarray.Each pixel incorporates two charge sensors:a diode sensor and a Topmetal sensor.The in-pixel circuit primarily consists of a charge-sensitive amplifier for energy measurements,a discriminator with a peak-holding circuit,and a time-to-amplitude converter for time-of-arrival measurements.The pixel of Topmetal-M2 has a charge input range of~0-3 k e-,a voltage output range of~0-180 mV,and a charge-voltage conversion gain of~59.56μV∕e-.The average equivalent noise charge of Topmetal-M2,which includes the readout electronic system noise,is~43.45 e-.In the scanning mode,the time resolution of Topmetal-M2 is 1 LSB=1.25μs,and the precision is^()7.41μs.At an operating voltage of 1.5 V,Topmetal-M2 has a power consumption of~49 mW∕cm~2.In this article,we provide a comprehensive overview of the chip architecture,pixel working principles,and functional behavior of Topmetal-M2.Furthermore,we present the results of preliminary tests conducted on Topmetal-M2,namely,alpha-particle and soft X-ray tests.
基金Project supported by the National Natural Science Foundation of China (Grant No 10675074)
文摘A chemical vapour deposition （CVD） diamond film detector was prepared and the main characteristics for pulsed proton detection were studied at Beijing Tandem Accelerator. The result shows that the charge collection efficiency of the detector increases with increasing electric field intensity and reaches to 9.44% at 5 V/μm with the charge collection distance of 15.9 μm. The relationship between the sensitivity of the detector and proton energy is consistent with the Monte Carlo （MC） simulation result. Its plasma time for a pulse with 4.85×10^5 protons is 1l.2ns. The dose threshold for onset of damage under 9MeV proton irradiation in the detector is about 10^13 cm^-2. All of the results show that a CVD diamond detector has fast time response and high radiation hardness, and can be used in pulsed proton detection.
文摘针对传统α能谱测量系统存在的本底噪声高、能量分辨率受限等问题,研制了基于FPGA技术的数字多道分析模块与PIPS半导体探测器相结合的新一代α能谱测量系统。该系统设计基于FPGA的多参数数字多道处理架构,利用硬件描述语言实现高速脉冲幅度提取算法,开发了自适应基线恢复技术和波形动态甄别机制。实验数据表明,该系统能量分辨率最低可达到16.293 ke V@5.486 MeV(FWHM),支持8192道能谱分析,具备多探测器同步采集能力,为环境放射性监测、核安全保障、食品安全等领域的超低水平α核素分析提供了可靠的技术手段。
文摘Microstructure of P + Si 0.65 Ge 0.35 /p Si HIP infrared detector has been studied by using localization cross section transmission electron microscopy. The photosensitive region of the detector consists of 6 P + Si 0.65 Ge 0.35 layers and 5 UD Si layers, which are flat and have thickness of 6 nm and 32 nm, respectively. A stress field exists on the interface between Si 0.65 Ge 0.35 and UD Si layers, but no any crystal defect has been found in this region, except the edges of this region. Both Si 0.65 Ge 0.35 and UD Si layers on amorphous SiO 2 layer consist of polycrystals and are in wave. There is defect area in the edges of photosensitive region. The area appears in a shape of inverse triangle and the maximum width is less than 120 nm. The crystal defects are stacking faults and microtwins.
文摘In recent years, the narrow bandgap antimonide based compound semiconductors (ABCS) are widely regarded as the first candidate materials for fabrication of the third generation infrared photon detectors and integrated circuits with ultra-high speed and ultra-low power consumption. Due to their unique bandgap structure and physical properties, it makes a vast space to develop various novel devices, and becomes a hot research area in many developed countries such as USA, Japan, Germany and Israel etc. Research progress in the preparation and application of ABCS materials, existing problems and some latest results are briefly introduced.
