Sensitive and reliable X-ray detectors are essential for medical radiography,industrial inspection and security screening.Lowering the radiation dose allows reduced health risks and increased frequency and fidelity of...Sensitive and reliable X-ray detectors are essential for medical radiography,industrial inspection and security screening.Lowering the radiation dose allows reduced health risks and increased frequency and fidelity of diagnostic technologies for earlier detection of disease and its recurrence.Three-dimensional(3 D)organic-inorganic hybrid lead halide perovskites are promising for direct X-ray detection-they show improved sensitivity compared to conventional X-ray detectors.However,their high and unstable dark current,caused by ion migration and high dark carrier concentration in the 3 D hybrid perovskites,limits their performance and long-term operation stability.Here we report ultrasensitive,stable X-ray detectors made using zero-dimensional(0 D)methylammonium bismuth iodide perovskite(MA3Bi2I9)single crystals.The 0 D crystal structure leads to a high activation energy(Ea)for ion migration(0.46 e V)and is also accompanied by a low dark carrier concentration(~10^6 cm^-3).The X-ray detectors exhibit sensitivity of 10,620μC Gy-1 air cm-2,a limit of detection(Lo D)of 0.62 nG yairs-1,and stable operation even under high applied biases;no deterioration in detection performance was observed following sensing of an integrated X-ray irradiation dose of^23,800 m Gyair,equivalent to>200,000 times the dose required for a single commercial X-ray chest radiograph.Regulating the ion migration channels and decreasing the dark carrier concentration in perovskites provide routes for stable and ultrasensitive X-ray detectors.展开更多
Nitrogen-doped, p-type ZnO thin films were grown successfully on sapphire (0001) substrates by using atomic layer epitaxy (ALE). Zn(C2H5)2 [Diethylzinc, DEZn], H2O and NH3 were used as a zinc precursor, an oxidant and...Nitrogen-doped, p-type ZnO thin films were grown successfully on sapphire (0001) substrates by using atomic layer epitaxy (ALE). Zn(C2H5)2 [Diethylzinc, DEZn], H2O and NH3 were used as a zinc precursor, an oxidant and a doping source gas, respectively. The lowest electrical resistivity of the p-type ZnO films grown by ALE and annealed at 1000 ℃ in an oxygen atmosphere for 1 h was 18.3 Ω·cm with a hole concentration of 3.71×1017 cm-3. Low temperature-photoluminescence analysis and time-dependent Hall measurement results support that the nitrogen-doped ZnO after annealing is a p-type semiconductor.展开更多
用融熔法研制了 In_2O_3和 ITO(In_2O_3掺杂 Sn)单晶,并对其光电性能进行研究.纯 ITO 是一种简并半导体,在常温下,以晶格声子散射为主要的载流子传输机理.对 ITO 单晶,给出了载流子浓度与 Sn 掺杂浓度及载流子迁移率的关系.并对在单晶...用融熔法研制了 In_2O_3和 ITO(In_2O_3掺杂 Sn)单晶,并对其光电性能进行研究.纯 ITO 是一种简并半导体,在常温下,以晶格声子散射为主要的载流子传输机理.对 ITO 单晶,给出了载流子浓度与 Sn 掺杂浓度及载流子迁移率的关系.并对在单晶中由于用助溶剂而引入的 Pb 掺杂对材料电性能的影响作了探讨.从材料的吸收光谱图中的本征吸收限的变化及 Plasma 频率和坡度的变化,证实了我们对电性能测试的结果.EXAFS 结构测试结果给出了这二种材料导电率变化的因素.展开更多
基金supported by the National Natural Science Foundation of China(Grant nos.21773218,61974063)the Sichuan Province(Grant no.2018JY0206)the China Academy of Engineering Physics(Grant no.YZJJLX2018007)。
文摘Sensitive and reliable X-ray detectors are essential for medical radiography,industrial inspection and security screening.Lowering the radiation dose allows reduced health risks and increased frequency and fidelity of diagnostic technologies for earlier detection of disease and its recurrence.Three-dimensional(3 D)organic-inorganic hybrid lead halide perovskites are promising for direct X-ray detection-they show improved sensitivity compared to conventional X-ray detectors.However,their high and unstable dark current,caused by ion migration and high dark carrier concentration in the 3 D hybrid perovskites,limits their performance and long-term operation stability.Here we report ultrasensitive,stable X-ray detectors made using zero-dimensional(0 D)methylammonium bismuth iodide perovskite(MA3Bi2I9)single crystals.The 0 D crystal structure leads to a high activation energy(Ea)for ion migration(0.46 e V)and is also accompanied by a low dark carrier concentration(~10^6 cm^-3).The X-ray detectors exhibit sensitivity of 10,620μC Gy-1 air cm-2,a limit of detection(Lo D)of 0.62 nG yairs-1,and stable operation even under high applied biases;no deterioration in detection performance was observed following sensing of an integrated X-ray irradiation dose of^23,800 m Gyair,equivalent to>200,000 times the dose required for a single commercial X-ray chest radiograph.Regulating the ion migration channels and decreasing the dark carrier concentration in perovskites provide routes for stable and ultrasensitive X-ray detectors.
文摘Nitrogen-doped, p-type ZnO thin films were grown successfully on sapphire (0001) substrates by using atomic layer epitaxy (ALE). Zn(C2H5)2 [Diethylzinc, DEZn], H2O and NH3 were used as a zinc precursor, an oxidant and a doping source gas, respectively. The lowest electrical resistivity of the p-type ZnO films grown by ALE and annealed at 1000 ℃ in an oxygen atmosphere for 1 h was 18.3 Ω·cm with a hole concentration of 3.71×1017 cm-3. Low temperature-photoluminescence analysis and time-dependent Hall measurement results support that the nitrogen-doped ZnO after annealing is a p-type semiconductor.
文摘用融熔法研制了 In_2O_3和 ITO(In_2O_3掺杂 Sn)单晶,并对其光电性能进行研究.纯 ITO 是一种简并半导体,在常温下,以晶格声子散射为主要的载流子传输机理.对 ITO 单晶,给出了载流子浓度与 Sn 掺杂浓度及载流子迁移率的关系.并对在单晶中由于用助溶剂而引入的 Pb 掺杂对材料电性能的影响作了探讨.从材料的吸收光谱图中的本征吸收限的变化及 Plasma 频率和坡度的变化,证实了我们对电性能测试的结果.EXAFS 结构测试结果给出了这二种材料导电率变化的因素.
