Significant advancement in thin-film cadmium telluride (CdTe) deposition techniques in recent years has made this material attractive for the development of low-cost large area detector. Here we evaluate the intrinsic...Significant advancement in thin-film cadmium telluride (CdTe) deposition techniques in recent years has made this material attractive for the development of low-cost large area detector. Here we evaluate the intrinsic performance of the detector for a range of energies relevant to diagnostic imaging applications, such as fluoroscopy. The input x-ray spectra for a set of tube potentials ranging from 70 to 140 kVp were computed with the tungsten anode spectral model using interpolating polynomials (TASMIP) based on the measured output of our diagnostic x-ray simulator. Frequency-dependent detector performance analysis was conducted through Monte Carlo simulations of energy deposition within the detector. Intrinsic modulation transfer functions (MTF), noise power spectra (NPS), and detective quantum efficiencies (DQE) were computed for a set of CdTe detectors of varying thickness, from 100 to 1000 μm. MTF behavior at higher frequencies was affected by thickness and input energy, NPS increased with film thickness and energy, and the resultant DQE(f) decreased with increasing the input energy, but increased with the thickness of the detector. We found that the optimal thickness of CdTe under diagnostic x-ray beam is in the range of 300 to 600 μm. Physical properties of CdTe, such as the high atomic number and density, used in direct detection configuration, together with the recently established thin-film manufacturing techniques makes this technology a promising photoconductor for large area diagnostic flat panel imaging.展开更多
Silver nanocluster embedded ZnO composite thin film was observed to have an angle-sensitive and fast photovoltaic effect in the angle range from -90° to 90° , its peak value and the polarity varied regularly...Silver nanocluster embedded ZnO composite thin film was observed to have an angle-sensitive and fast photovoltaic effect in the angle range from -90° to 90° , its peak value and the polarity varied regularly with the angle of incidence of the 1.064-μm pulsed Nd：YAG laser radiation onto the ZnO surface. Meanwhile, for each photovoltaic signal, its rising time reached -2 ns with an open-circuit photovoltage of -2 ns full width at half-maximum. This angle-sensitive fast photovoltaic effect is expected to put this composite film a candidate for angle-sensitive and fast photodetector.展开更多
Ferroelectric Ba0.65Sr0.35TiO3 （BST） thin films on the Pt/Ti/SiO2/Si substrate have been successfully prepared by sol-gel. Such films have approximately 300 nm thicknesses with a remnant polarization of about 2.95 ...Ferroelectric Ba0.65Sr0.35TiO3 （BST） thin films on the Pt/Ti/SiO2/Si substrate have been successfully prepared by sol-gel. Such films have approximately 300 nm thicknesses with a remnant polarization of about 2.95 μ℃/cm^2 and a coercive field of about 21.5 kV/cm. The investigations of X-ray diffraction and atomic force microscopy show that the BST films annealed at 650 ℃ exhibit a tetragonal structure and that the films dominantly consist of large column or grains of about 89 nm in diameter. The curves of the temperature dependence of dielectric coefficient in different frequencies display the curie transition at the temperature around 23 ℃. The dielectric loss tangent of BST thin fdms at 100 kHz is less than 0.04. As a result, the BST thin films are more applicable for fabrication of infrared detector compared with the BST thin films reported previously.展开更多
针对锰钴镍氧化物薄膜型红外探测器的结构特点,提出了一种红外探测器低频噪声长时间监测系统设计方案,并进行了测试验证。监测系统采用低噪声偏置电源激发红外探测器的低频噪声,然后将该低频噪声信号通过设计的高性能前置放大器放大,利...针对锰钴镍氧化物薄膜型红外探测器的结构特点,提出了一种红外探测器低频噪声长时间监测系统设计方案,并进行了测试验证。监测系统采用低噪声偏置电源激发红外探测器的低频噪声,然后将该低频噪声信号通过设计的高性能前置放大器放大,利用基于PC的硬件平台采集放大后的噪声信号,最后通过编写的算法提取噪声信号的各种参量。实际测试结果表明,该监测系统能在10 k Hz的采样率下连续30 d不间断采集探测器的低频噪声,并实时计算噪声信号的峰峰值、均方值、功率谱密度等参数,频率分辨率可达到0.05 Hz。展开更多
采用由多孔 Si O2 薄膜和过渡 Si O2 薄膜组成的复合薄膜结构实现了非制冷热释电薄膜红外探测器的热绝缘 .利用溶胶凝胶方法制备了多孔 Si O2 薄膜以及过渡 Si O2 薄膜 ,通过优化制备工艺 ,使得多孔 Si O2 一次成膜厚度达到30 70 nm ,...采用由多孔 Si O2 薄膜和过渡 Si O2 薄膜组成的复合薄膜结构实现了非制冷热释电薄膜红外探测器的热绝缘 .利用溶胶凝胶方法制备了多孔 Si O2 薄膜以及过渡 Si O2 薄膜 ,通过优化制备工艺 ,使得多孔 Si O2 一次成膜厚度达到30 70 nm ,孔率达到 5 9% ;过渡 Si O2 一次成膜的厚度达到 1 88nm,孔率达到 4 % .AFM表明 ,由过渡 Si O2 薄膜与多孔Si O2 组成的复合薄膜结构的表面粗糙度远小于多孔 Si O2 薄膜的表面粗糙度 .展开更多
文摘Significant advancement in thin-film cadmium telluride (CdTe) deposition techniques in recent years has made this material attractive for the development of low-cost large area detector. Here we evaluate the intrinsic performance of the detector for a range of energies relevant to diagnostic imaging applications, such as fluoroscopy. The input x-ray spectra for a set of tube potentials ranging from 70 to 140 kVp were computed with the tungsten anode spectral model using interpolating polynomials (TASMIP) based on the measured output of our diagnostic x-ray simulator. Frequency-dependent detector performance analysis was conducted through Monte Carlo simulations of energy deposition within the detector. Intrinsic modulation transfer functions (MTF), noise power spectra (NPS), and detective quantum efficiencies (DQE) were computed for a set of CdTe detectors of varying thickness, from 100 to 1000 μm. MTF behavior at higher frequencies was affected by thickness and input energy, NPS increased with film thickness and energy, and the resultant DQE(f) decreased with increasing the input energy, but increased with the thickness of the detector. We found that the optimal thickness of CdTe under diagnostic x-ray beam is in the range of 300 to 600 μm. Physical properties of CdTe, such as the high atomic number and density, used in direct detection configuration, together with the recently established thin-film manufacturing techniques makes this technology a promising photoconductor for large area diagnostic flat panel imaging.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.60877038,50672132,60778034 and 10804077)Program for New Century Excellent Talents in University,Research Fund for the Doctoral Program of the Higher Education of China(Grant No.200804250006)+1 种基金Key Project of the Chinese Ministry of Education(Grant No.107020)the Natural Science Foundation of Beijing(Grant No.4082026)
文摘Silver nanocluster embedded ZnO composite thin film was observed to have an angle-sensitive and fast photovoltaic effect in the angle range from -90° to 90° , its peak value and the polarity varied regularly with the angle of incidence of the 1.064-μm pulsed Nd：YAG laser radiation onto the ZnO surface. Meanwhile, for each photovoltaic signal, its rising time reached -2 ns with an open-circuit photovoltage of -2 ns full width at half-maximum. This angle-sensitive fast photovoltaic effect is expected to put this composite film a candidate for angle-sensitive and fast photodetector.
文摘Ferroelectric Ba0.65Sr0.35TiO3 （BST） thin films on the Pt/Ti/SiO2/Si substrate have been successfully prepared by sol-gel. Such films have approximately 300 nm thicknesses with a remnant polarization of about 2.95 μ℃/cm^2 and a coercive field of about 21.5 kV/cm. The investigations of X-ray diffraction and atomic force microscopy show that the BST films annealed at 650 ℃ exhibit a tetragonal structure and that the films dominantly consist of large column or grains of about 89 nm in diameter. The curves of the temperature dependence of dielectric coefficient in different frequencies display the curie transition at the temperature around 23 ℃. The dielectric loss tangent of BST thin fdms at 100 kHz is less than 0.04. As a result, the BST thin films are more applicable for fabrication of infrared detector compared with the BST thin films reported previously.
文摘针对锰钴镍氧化物薄膜型红外探测器的结构特点,提出了一种红外探测器低频噪声长时间监测系统设计方案,并进行了测试验证。监测系统采用低噪声偏置电源激发红外探测器的低频噪声,然后将该低频噪声信号通过设计的高性能前置放大器放大,利用基于PC的硬件平台采集放大后的噪声信号,最后通过编写的算法提取噪声信号的各种参量。实际测试结果表明,该监测系统能在10 k Hz的采样率下连续30 d不间断采集探测器的低频噪声,并实时计算噪声信号的峰峰值、均方值、功率谱密度等参数,频率分辨率可达到0.05 Hz。
