High-purity germanium(HPGe)detectors,which are used for direct dark matter detection,have the advantages of a low threshold and excellent energy resolution.The surface passivation of HPGe has become crucial for achiev...High-purity germanium(HPGe)detectors,which are used for direct dark matter detection,have the advantages of a low threshold and excellent energy resolution.The surface passivation of HPGe has become crucial for achieving an extremely low energy threshold.In this study,first-principles simulations,passivation film preparation,and metal oxide semiconductor(MOS)capacitor characterization were combined to study surface passivation.Theoretical calculations of the energy band structure of the -H,-OH,and -NH_(2) passivation groups on the surface of Ge were performed,and the interface state density and potential with five different passivation groups with N/O atomic ratios were accurately analyzed to obtain a stable surface state.Based on the theoretical calculation results,the surface passivation layers of the Ge_(2)ON_(2) film were prepared via magnetron sputtering in accordance with the optimum atomic ratio structure.The microstructure,C-V,and I-V electrical properties of the layers,and the passivation effect of the Al/Ge_(2)ON_(2)/Ge MOS were characterized to test the interface state density.The mean interface state density obtained by the Terman method was 8.4×10^(11) cm^(-2) eV^(-1).The processing of germanium oxynitrogen passivation films is expected to be used in direct dark matter detection of the HPGe detector surface passivation technology to reduce the detector leakage currents.展开更多
To detect radioactive substances with low activity levels,an anticoincidence detector and a high-purity germanium(HPGe)detector are typically used simultaneously to suppress Compton scattering background,thereby resul...To detect radioactive substances with low activity levels,an anticoincidence detector and a high-purity germanium(HPGe)detector are typically used simultaneously to suppress Compton scattering background,thereby resulting in an extremely low detection limit and improving the measurement accuracy.However,the complex and expensive hardware required does not facilitate the application or promotion of this method.Thus,a method is proposed in this study to discriminate the digital waveform of pulse signals output using an HPGe detector,whereby Compton scattering background is suppressed and a low minimum detectable activity(MDA)is achieved without using an expensive and complex anticoincidence detector and device.The electric-field-strength and energy-deposition distributions of the detector are simulated to determine the relationship between pulse shape and energy-deposition location,as well as the characteristics of energy-deposition distributions for fulland partial-energy deposition events.This relationship is used to develop a pulse-shape-discrimination algorithm based on an artificial neural network for pulse-feature identification.To accurately determine the relationship between the deposited energy of gamma(γ)rays in the detector and the deposition location,we extract four shape parameters from the pulse signals output by the detector.Machine learning is used to input the four shape parameters into the detector.Subsequently,the pulse signals are identified and classified to discriminate between partial-and full-energy deposition events.Some partial-energy deposition events are removed to suppress Compton scattering.The proposed method effectively decreases the MDA of an HPGeγ-energy dispersive spectrometer.Test results show that the Compton suppression factors for energy spectra obtained from measurements on ^(152)Eu,^(137)Cs,and ^(60)Co radioactive sources are 1.13(344 keV),1.11(662 keV),and 1.08(1332 keV),respectively,and that the corresponding MDAs are 1.4%,5.3%,and 21.6%lower,respectively.展开更多
Poly-crystalline silicon thin film has big potential of reducing the cost of solar cells. In this paper the preparation of thin film is introduced, and then the morphology of poly-crystalline thin film, is discussed. ...Poly-crystalline silicon thin film has big potential of reducing the cost of solar cells. In this paper the preparation of thin film is introduced, and then the morphology of poly-crystalline thin film, is discussed. On the film we developed poly-crystalline silicon thin film solar cells with efficiency up to 6.05% without anti-reflection coating.展开更多
High-performance germanium(Ge)waveguide photodetectors are designed and fabricated utilizing the inductivegain-peaking technique.With the appropriate integrated inductors,the 3-dB bandwidth of photodetectors is signif...High-performance germanium(Ge)waveguide photodetectors are designed and fabricated utilizing the inductivegain-peaking technique.With the appropriate integrated inductors,the 3-dB bandwidth of photodetectors is significantly improved owing to the inductive-gain-peaking effect without any compromises to the dark current and optical responsivity.Measured 3-dB bandwidth up to 75 GHz is realized and clear open eye diagrams at 64 Gbps are observed.In this work,the relationship between the frequency response and large signal transmission characteristics on the integrated inductors of Ge waveguide photodetectors is investigated,which indicates the high-speed performance of photodetectors using the inductive-gainpeaking technique.展开更多
The process of thermal stress damage during 1080 nm laser ablation of single-crystal germanium was recorded in real time using a high-speed charge-coupled device.A three-dimensional finite element numerical model base...The process of thermal stress damage during 1080 nm laser ablation of single-crystal germanium was recorded in real time using a high-speed charge-coupled device.A three-dimensional finite element numerical model based on Fourier's heat conduction equation,Hooke's law and the Alexander–Hasson equation was developed to analyze the thermal stress damage mechanism involved.The damage morphology of the ablated samples was observed using an optical microscope.The results show that the cooling process has an important influence on fracture in the laser-irradiated region of single-crystal germanium.Fracture is the result of a combination of thermal stress and reduction in local yield strength.展开更多
煤系伴生资源提取不可避免产生大量低浓度含锗废液,导致稀散金属锗资源的流失,并污染环境。采用酒石酸改性铁锰氧化物(JFMBO)作为吸附材料富集回收煤浸出液中低浓度锗,通过XRD、BET、Zeta电位等测试手段研究了JFMBO的晶体结构和表面性...煤系伴生资源提取不可避免产生大量低浓度含锗废液,导致稀散金属锗资源的流失,并污染环境。采用酒石酸改性铁锰氧化物(JFMBO)作为吸附材料富集回收煤浸出液中低浓度锗,通过XRD、BET、Zeta电位等测试手段研究了JFMBO的晶体结构和表面性质等特征,并探究了JFMBO对锗的吸附行为。结果表明,改性铁锰氧化物吸附锗的最佳投加量为2 g L;JFMBO对锗的吸附容量与溶液pH呈现正相关的趋势;JFMBO对锗的吸附容量随离子强度的增大而降低,升高温度有助于JFMBO对锗吸附反应的进行。锗在JFMBO上的吸附过程可用准二级动力学方程描述,吸附等温线更符合Langmuir模型,25℃下锗的最大饱和吸附容量为169.535μmol g。JFMBO可再生使用,循环进行3次吸附-脱附后仍可保持较高的吸附效率。展开更多
基金supported by the National Natural Science Foundation of China(No.12005017).
文摘High-purity germanium(HPGe)detectors,which are used for direct dark matter detection,have the advantages of a low threshold and excellent energy resolution.The surface passivation of HPGe has become crucial for achieving an extremely low energy threshold.In this study,first-principles simulations,passivation film preparation,and metal oxide semiconductor(MOS)capacitor characterization were combined to study surface passivation.Theoretical calculations of the energy band structure of the -H,-OH,and -NH_(2) passivation groups on the surface of Ge were performed,and the interface state density and potential with five different passivation groups with N/O atomic ratios were accurately analyzed to obtain a stable surface state.Based on the theoretical calculation results,the surface passivation layers of the Ge_(2)ON_(2) film were prepared via magnetron sputtering in accordance with the optimum atomic ratio structure.The microstructure,C-V,and I-V electrical properties of the layers,and the passivation effect of the Al/Ge_(2)ON_(2)/Ge MOS were characterized to test the interface state density.The mean interface state density obtained by the Terman method was 8.4×10^(11) cm^(-2) eV^(-1).The processing of germanium oxynitrogen passivation films is expected to be used in direct dark matter detection of the HPGe detector surface passivation technology to reduce the detector leakage currents.
基金This work was supported by the National Key R&D Program of China(Nos.2022YFF0709503,2022YFB1902700,2017YFC0602101)the Key Research and Development Program of Sichuan province(No.2023YFG0347)the Key Research and Development Program of Sichuan province(No.2020ZDZX0007).
文摘To detect radioactive substances with low activity levels,an anticoincidence detector and a high-purity germanium(HPGe)detector are typically used simultaneously to suppress Compton scattering background,thereby resulting in an extremely low detection limit and improving the measurement accuracy.However,the complex and expensive hardware required does not facilitate the application or promotion of this method.Thus,a method is proposed in this study to discriminate the digital waveform of pulse signals output using an HPGe detector,whereby Compton scattering background is suppressed and a low minimum detectable activity(MDA)is achieved without using an expensive and complex anticoincidence detector and device.The electric-field-strength and energy-deposition distributions of the detector are simulated to determine the relationship between pulse shape and energy-deposition location,as well as the characteristics of energy-deposition distributions for fulland partial-energy deposition events.This relationship is used to develop a pulse-shape-discrimination algorithm based on an artificial neural network for pulse-feature identification.To accurately determine the relationship between the deposited energy of gamma(γ)rays in the detector and the deposition location,we extract four shape parameters from the pulse signals output by the detector.Machine learning is used to input the four shape parameters into the detector.Subsequently,the pulse signals are identified and classified to discriminate between partial-and full-energy deposition events.Some partial-energy deposition events are removed to suppress Compton scattering.The proposed method effectively decreases the MDA of an HPGeγ-energy dispersive spectrometer.Test results show that the Compton suppression factors for energy spectra obtained from measurements on ^(152)Eu,^(137)Cs,and ^(60)Co radioactive sources are 1.13(344 keV),1.11(662 keV),and 1.08(1332 keV),respectively,and that the corresponding MDAs are 1.4%,5.3%,and 21.6%lower,respectively.
基金This work was supported by the Chinese Academy of Sciences within the Hundred Talent Project(No.99-019-422288)National High Technical Research and Development Programme of China(No.2001AA513060).
文摘Poly-crystalline silicon thin film has big potential of reducing the cost of solar cells. In this paper the preparation of thin film is introduced, and then the morphology of poly-crystalline thin film, is discussed. On the film we developed poly-crystalline silicon thin film solar cells with efficiency up to 6.05% without anti-reflection coating.
基金supported by the National Key Research and Development Program of China(2020YFB2206103)National Natural Science Foundation of China(61975196)Youth Innovation Promotion Association Chinese Academy of Sciences(2021111)。
文摘High-performance germanium(Ge)waveguide photodetectors are designed and fabricated utilizing the inductivegain-peaking technique.With the appropriate integrated inductors,the 3-dB bandwidth of photodetectors is significantly improved owing to the inductive-gain-peaking effect without any compromises to the dark current and optical responsivity.Measured 3-dB bandwidth up to 75 GHz is realized and clear open eye diagrams at 64 Gbps are observed.In this work,the relationship between the frequency response and large signal transmission characteristics on the integrated inductors of Ge waveguide photodetectors is investigated,which indicates the high-speed performance of photodetectors using the inductive-gainpeaking technique.
文摘The process of thermal stress damage during 1080 nm laser ablation of single-crystal germanium was recorded in real time using a high-speed charge-coupled device.A three-dimensional finite element numerical model based on Fourier's heat conduction equation,Hooke's law and the Alexander–Hasson equation was developed to analyze the thermal stress damage mechanism involved.The damage morphology of the ablated samples was observed using an optical microscope.The results show that the cooling process has an important influence on fracture in the laser-irradiated region of single-crystal germanium.Fracture is the result of a combination of thermal stress and reduction in local yield strength.
文摘煤系伴生资源提取不可避免产生大量低浓度含锗废液,导致稀散金属锗资源的流失,并污染环境。采用酒石酸改性铁锰氧化物(JFMBO)作为吸附材料富集回收煤浸出液中低浓度锗,通过XRD、BET、Zeta电位等测试手段研究了JFMBO的晶体结构和表面性质等特征,并探究了JFMBO对锗的吸附行为。结果表明,改性铁锰氧化物吸附锗的最佳投加量为2 g L;JFMBO对锗的吸附容量与溶液pH呈现正相关的趋势;JFMBO对锗的吸附容量随离子强度的增大而降低,升高温度有助于JFMBO对锗吸附反应的进行。锗在JFMBO上的吸附过程可用准二级动力学方程描述,吸附等温线更符合Langmuir模型,25℃下锗的最大饱和吸附容量为169.535μmol g。JFMBO可再生使用,循环进行3次吸附-脱附后仍可保持较高的吸附效率。
