目的为了提高脾脏炎性肌纤维母细胞瘤的诊断水平,探讨多模态影像学的价值。方法回顾分析本院1例成人脾炎性肌纤维母细胞瘤(inflammatory pseudotumor of spleen,SIMT)患者的影像资料,包括彩色超声、CT平扫及增强、MRI平扫,并复习文献。...目的为了提高脾脏炎性肌纤维母细胞瘤的诊断水平,探讨多模态影像学的价值。方法回顾分析本院1例成人脾炎性肌纤维母细胞瘤(inflammatory pseudotumor of spleen,SIMT)患者的影像资料,包括彩色超声、CT平扫及增强、MRI平扫,并复习文献。结果脾脏内数枚肿块,以低回声为主,回声不均,边界尚清,形态规整,内见少许血流信号。CT平扫为等密度,其内见小片状低密度区;增强后呈轻度至中度不均匀强化。MRI表现:T1WI上低或等信号,T2WI序列及T2WI抑脂序列为等及高信号,病灶周围见完整包膜,DWI图为等及高信号,信号不均匀。病理学及免疫组化结果为SIMT;EB病毒(+)。结论SIMT临床表现缺乏特异性,最终需病理学确诊。多模态影像学检查对脾炎性肌纤维母细胞瘤有很高的诊断和鉴别诊断价值。展开更多
We demonstrate that the Mg-doping in barriers can partially screen the polarization fields of InGaN-based green light-emitting diodes.The photocurrent spectra show that the Mg-doping samples have smaller polarization ...We demonstrate that the Mg-doping in barriers can partially screen the polarization fields of InGaN-based green light-emitting diodes.The photocurrent spectra show that the Mg-doping samples have smaller polarization fields and the blue shift of the peak with increasing current is observed.The reduction of polarization fields can be attributed to the screening of the impurity holes generated by the Mg atoms in the barriers.The efficiency droop is sensitive to the Mg-doping concentration in barriers,while the sample with Mg concentration of 5×10^(19) cm^(-3) exhibits the lowest efficiency degradation of 12.4%at a high injection current.展开更多
The electromagnetic interaction between Ag nanoparticles on the top of the Si substrate and the incident light has been studied by numerical simulations. It is found that the presence of dielectric layers with differe...The electromagnetic interaction between Ag nanoparticles on the top of the Si substrate and the incident light has been studied by numerical simulations. It is found that the presence of dielectric layers with different thicknesses leads to the varied resonance wavelength and scattering cross section and consequently the shifted photocurrent response for all wavelengths. These different behaviours are determined by whether the dielectric layer is beyond the domain where the elcetric field of metallic plasmons takes effect, combined with the effect of geometrical optics. It is revealed that for particles of a certain size, an appropriate dielectric thickness is desirable to achieve the best absorption. For a certain thickness of spacer, an appropriate granular size is also desirable. These observations have substantial applications for the optimization of surface plasmon enhanced silicon solar cells.展开更多
Undoped AlInGaN epilayers on GaN templates with different hydrogen(H_(2))and nitrogen(N_(2))carrier gas ratios(1:8,2:8,and 3:8 as samples 1,2 and 3,respectively)were grown.When the flow ratio of H_(2) and N_(2) rises ...Undoped AlInGaN epilayers on GaN templates with different hydrogen(H_(2))and nitrogen(N_(2))carrier gas ratios(1:8,2:8,and 3:8 as samples 1,2 and 3,respectively)were grown.When the flow ratio of H_(2) and N_(2) rises from 1:8 to 3:8,an indium composition decrease from 3%to 1.2%is observed while the aluminum content stays constant at any flow ratio.Due to the quantum-dot-like effect,photoluminescence intensity is enhanced in the sample with the low carrier gas flow ratio of H_(2)/N_(2).However,the potential well caused by indium uneven distribution is nonuniform,which is more severe in the sample with carrier gas flow ratio 1:8.The process of carrier transfer from shallow to deep potential wells would be more difficult to accomplish,resulting in the reduction of the photoluminescence intensity.This is found to be consistent with the carriers'lifetime with the help of time-resolved photoluminescence.展开更多
An Inx Ga1_xN/lnN quantum-dot intermediate-band solar cell is calculated by means of solving the Schrodinger equation according to the Kronig-Penney model. Based on particular assumptions, the power conversion efficie...An Inx Ga1_xN/lnN quantum-dot intermediate-band solar cell is calculated by means of solving the Schrodinger equation according to the Kronig-Penney model. Based on particular assumptions, the power conversion efficiency is worked out. The results reveal that the InxGa1- xN/InN quantum-dot intermediate-band solar cell manifests much larger power conversion efficiency than that of p-n junction solar cells, and the power conversion efficiency strongly depends on the size of the quantum dot and the interdot distance.展开更多
Yellow and blue luminescence in undoped GaN layers with different resistivities are studied by cathodoluminescence.Intense yellow and blue luminescence bands are observed in semi-insulating GaN,while in n-GaN the yell...Yellow and blue luminescence in undoped GaN layers with different resistivities are studied by cathodoluminescence.Intense yellow and blue luminescence bands are observed in semi-insulating GaN,while in n-GaN the yellow luminescence and blue luminescence bands are very weak.The stronger yellow and blue luminescences in semi-insulating GaN are correlated to the higher edge-type dislocation density.The scanning cathodoluminescence image reveals strong defect-related luminescence at the grain boundaries where the dislocations accumulate.It is found that the relative intensity of the blue luminescence band to the yellow luminescence band increases with the cathodoluminescence beam energies and is larger in n-GaN with a lower density of edge-type dislocations.An approximately 3.35eV shoulder next to the near-band-edge peak is observed in n-GaN but not in semi-insulating GaN.A redshift of the near-band-edge peak with cathodoluminescence beam energy is observed in both samples and is explained by internal absorption.展开更多
In this paper,the anisotropic etching process of Si(100) wafers in tetramethyl ammonium hydroxide(TMAH) solution with isopropyl alcohol(IPA) is investigated in detail. An inverted trapezoidal pattern is developed. A s...In this paper,the anisotropic etching process of Si(100) wafers in tetramethyl ammonium hydroxide(TMAH) solution with isopropyl alcohol(IPA) is investigated in detail. An inverted trapezoidal pattern is developed. A series of experiments are performed by changing TMAH concentration,IPA concentration,etching temperature and etching time. The structure of inverted trapezoidal patterns and roughness of the bottom surface are characterized by scanning electron microscopy(SEM) and atomic force microscopy(AFM). The results show that with TMAH concentration increases,the roughness of bottom surface will decrease. The addition of IPA into TMAH solution improves the morphology of the bottom surface significantly. Low temperature is beneficial to get a smooth bottom surface. Furthermore,etching time can change the bottom surface roughness. A model is proposed to explain the etching processes. The hillock area ratio of the bottom surface has the same tendency as the etching area ratio. Finally,smooth silicon inverted trapezoidal patterns are obtained for epitaxial growth of Ga N-based light emitting diode(LED) devices.展开更多
文摘目的为了提高脾脏炎性肌纤维母细胞瘤的诊断水平,探讨多模态影像学的价值。方法回顾分析本院1例成人脾炎性肌纤维母细胞瘤(inflammatory pseudotumor of spleen,SIMT)患者的影像资料,包括彩色超声、CT平扫及增强、MRI平扫,并复习文献。结果脾脏内数枚肿块,以低回声为主,回声不均,边界尚清,形态规整,内见少许血流信号。CT平扫为等密度,其内见小片状低密度区;增强后呈轻度至中度不均匀强化。MRI表现:T1WI上低或等信号,T2WI序列及T2WI抑脂序列为等及高信号,病灶周围见完整包膜,DWI图为等及高信号,信号不均匀。病理学及免疫组化结果为SIMT;EB病毒(+)。结论SIMT临床表现缺乏特异性,最终需病理学确诊。多模态影像学检查对脾炎性肌纤维母细胞瘤有很高的诊断和鉴别诊断价值。
基金Supported by the Science and Technology Plan of the State Ministry of Science and Technology(No 2011BAE01B17).
文摘We demonstrate that the Mg-doping in barriers can partially screen the polarization fields of InGaN-based green light-emitting diodes.The photocurrent spectra show that the Mg-doping samples have smaller polarization fields and the blue shift of the peak with increasing current is observed.The reduction of polarization fields can be attributed to the screening of the impurity holes generated by the Mg atoms in the barriers.The efficiency droop is sensitive to the Mg-doping concentration in barriers,while the sample with Mg concentration of 5×10^(19) cm^(-3) exhibits the lowest efficiency degradation of 12.4%at a high injection current.
基金supported by the National Basic Research Program of China (Grant Nos.2010CB934104 and 2010CB933800)the National Natural Science Foundation of China (Grant Nos.60606024 and 61076077)
文摘The electromagnetic interaction between Ag nanoparticles on the top of the Si substrate and the incident light has been studied by numerical simulations. It is found that the presence of dielectric layers with different thicknesses leads to the varied resonance wavelength and scattering cross section and consequently the shifted photocurrent response for all wavelengths. These different behaviours are determined by whether the dielectric layer is beyond the domain where the elcetric field of metallic plasmons takes effect, combined with the effect of geometrical optics. It is revealed that for particles of a certain size, an appropriate dielectric thickness is desirable to achieve the best absorption. For a certain thickness of spacer, an appropriate granular size is also desirable. These observations have substantial applications for the optimization of surface plasmon enhanced silicon solar cells.
基金Supported by the National High-Technology Research and Development Program of China under Grant No 2011AA03A105.
文摘Undoped AlInGaN epilayers on GaN templates with different hydrogen(H_(2))and nitrogen(N_(2))carrier gas ratios(1:8,2:8,and 3:8 as samples 1,2 and 3,respectively)were grown.When the flow ratio of H_(2) and N_(2) rises from 1:8 to 3:8,an indium composition decrease from 3%to 1.2%is observed while the aluminum content stays constant at any flow ratio.Due to the quantum-dot-like effect,photoluminescence intensity is enhanced in the sample with the low carrier gas flow ratio of H_(2)/N_(2).However,the potential well caused by indium uneven distribution is nonuniform,which is more severe in the sample with carrier gas flow ratio 1:8.The process of carrier transfer from shallow to deep potential wells would be more difficult to accomplish,resulting in the reduction of the photoluminescence intensity.This is found to be consistent with the carriers'lifetime with the help of time-resolved photoluminescence.
文摘An Inx Ga1_xN/lnN quantum-dot intermediate-band solar cell is calculated by means of solving the Schrodinger equation according to the Kronig-Penney model. Based on particular assumptions, the power conversion efficiency is worked out. The results reveal that the InxGa1- xN/InN quantum-dot intermediate-band solar cell manifests much larger power conversion efficiency than that of p-n junction solar cells, and the power conversion efficiency strongly depends on the size of the quantum dot and the interdot distance.
基金Supported by the Knowledge Innovation Project of Chinese Academy of Sciences(Nos YYYJ-0701-02,ISCAS2008T01,ISCAS2009L01 and ISCAS2009L02)the National Natural Sciences Foundation of China(Nos 60890193 and 60906006)and the National Basic Research Program of China(Nos 2006CB604905 and 2010CB327503).
文摘Yellow and blue luminescence in undoped GaN layers with different resistivities are studied by cathodoluminescence.Intense yellow and blue luminescence bands are observed in semi-insulating GaN,while in n-GaN the yellow luminescence and blue luminescence bands are very weak.The stronger yellow and blue luminescences in semi-insulating GaN are correlated to the higher edge-type dislocation density.The scanning cathodoluminescence image reveals strong defect-related luminescence at the grain boundaries where the dislocations accumulate.It is found that the relative intensity of the blue luminescence band to the yellow luminescence band increases with the cathodoluminescence beam energies and is larger in n-GaN with a lower density of edge-type dislocations.An approximately 3.35eV shoulder next to the near-band-edge peak is observed in n-GaN but not in semi-insulating GaN.A redshift of the near-band-edge peak with cathodoluminescence beam energy is observed in both samples and is explained by internal absorption.
基金supported by the National Natural Science Foundation of China(Nos.51472229,61422405,51202238,61306051 and 61474109)the “100 Talent Program” of Chinese Academy of Sciencesthe Opening Funding of State Key Lab of Silicon Materials(No.SKL2014-4)
文摘In this paper,the anisotropic etching process of Si(100) wafers in tetramethyl ammonium hydroxide(TMAH) solution with isopropyl alcohol(IPA) is investigated in detail. An inverted trapezoidal pattern is developed. A series of experiments are performed by changing TMAH concentration,IPA concentration,etching temperature and etching time. The structure of inverted trapezoidal patterns and roughness of the bottom surface are characterized by scanning electron microscopy(SEM) and atomic force microscopy(AFM). The results show that with TMAH concentration increases,the roughness of bottom surface will decrease. The addition of IPA into TMAH solution improves the morphology of the bottom surface significantly. Low temperature is beneficial to get a smooth bottom surface. Furthermore,etching time can change the bottom surface roughness. A model is proposed to explain the etching processes. The hillock area ratio of the bottom surface has the same tendency as the etching area ratio. Finally,smooth silicon inverted trapezoidal patterns are obtained for epitaxial growth of Ga N-based light emitting diode(LED) devices.
