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1.
电子束辐照对GaN基LED发光性能的影响   总被引:1,自引:1,他引:0       下载免费PDF全文
研究了不同能量的电子束辐照对GaN基发光二极管(Light emitting diode,LED)发光性能的影响。利用实验室提供的电子束模拟空间电子辐射,对GaN基LED外延片进行1.5,3.0,4.5 MeV电子束辐照实验,并应用光致发光(Photoluminescence,PL)谱测试发光性能。结果表明:在1.5 MeV电子束辐照下,采用10 kGy剂量辐照时,LED的发光强度增加约25%;而在100 kGy剂量辐照时,LED的发光强度降低约16%。3 MeV的电子束辐照可使原来色纯度不高的LED的色纯度变好,而更高能量的辐照将会引起器件失效。  相似文献
2.
A feasible and convenient method is proposed to suppress higher-harmonics for a varied-line-spacing plane grating monochromator in the soft X-ray region. Related calculations and experiments demonstrate that decreasing the included angle slightly by changing the parameter of the exit arm length can significantly improve light purity. This method is suitable and has been used for experiments of detector calibration in beamline 4B7B at the Beijing Synchrotron Radiation Facility (BSRF).  相似文献
3.
X-ray magnetic circular dichroism (XMCD) has become an important and powerful tool because it allows the study of material properties in combination with elemental specificity, chemical state specificity, and magnetic specificity. A new soft X-ray magnetic circular dichroism apparatus has been developed at the Beijing Synchrotron Radiation Facility (BSRF). The apparatus combines three experimental conditions: an ultra-high-vacuum environment, moderate magnetic fields and in-situ sample preparation to measure the absorption signal. We designed a C-type dipole electromagnet that provides magnetic fields up to 0.5 T in parallel (or anti-parallel) direction relative to the incoming X-ray beam. The performances of the electromagnet are measured and the results show good agreement with the simulation ones. Following film grown in situ by evaporation methods, XMCD measurements are performed. Combined polarization corrections, the magnetic moments of the Fe and Co films determined by sum rules are consistent with other theoretical predictions and experimental measurements.  相似文献
4.
Metal-organic chemical vapor deposition (MOCVD) grown ferromagnetic GaMnN films are investigated by photo- luminescence (PL) measurement with a mid-gap excitation wavelength of 405 nm. A sharp PL peak at 1.8 eV is found and the PL intensity successively decreases with the addition of Mn, in which the Mn concentration of sample A is below 1% ([Mn]A =0.75%) but its PL intensity is stronger than other samples'. The 1.8-eV PL peak is attributed to the recombination of electrons in the t2 state of the neutral Mn3+ acceptor with holes in the valence band. With Mn concentration increasing, the intensity of the PL peak decreases and the magnetic increment reduces in our samples. The correlation between the PL peak intensity and ferromagnetism of the samples is discussed in combination with the experimental results.  相似文献
5.
An investigation of room-temperature Raman scattering is carried out on ferromagnetic semiconductor GaMnN films grown by metalorganic chemical vapour deposition with different Mn content values. New bands around 300 and 669 cm-1, that are not observed in undoped GaN, are found. They are assigned to disorder-activated mode and local vibration mode (LVM), respectively. After annealing, the intensity ratio between the LVM and E2 (high) mode, i.e., ILVM /IE2 (high) , increases. The LO phonon-plasmon coupled (LOPC) mode is found in GaMnN, and the frequency of the LOPC mode of GaMnN shifting toward higher side is observed with the increase in the Mn doping in GaN. The ferromagnetic character and the carrier density of our GaMnN sample are discussed.  相似文献
6.
根据激光光源的特点,设计了一种基于蓝色半导体激光器的汽车远光灯系统。采用以Monge-Ampere方程为基础的自由曲面透镜设计,解决了激光光源能量密度高、发光面积小的问题;依据非成像光学理论,建立了透镜表面与目标面的映射关系;通过求解Monge-Ampere方程得出自由曲面上的坐标点,拟合坐标点得到自由曲面透镜模型;采用光学软件Tracepro进行了仿真分析。结果表明:照度最大值值为119.3lx,中心点照度为117.6lx,完全符合GB25991-2010标准,且光型分布均匀。  相似文献
7.
利用圆环形LED光源阵列结构,结合反射杯与自由曲面透镜的混合型配光,设计了可以实现对汽车前照灯远光和近光同时配光的光学系统.对经反射器聚光后的光线及配光屏幕进行了适当的网格划分,根据能量守恒定律,建立了出光角、自由曲面透镜与配光屏幕之间的坐标关系.结合折射定律,通过迭代计算得到自由曲面透镜上的点坐标,并使用三维建模软件得到透镜模型.利用Tracepro软件对光学系统模型进行了光线追迹.结果表明,所设计的光学系统可以同时满足GB 25991-2010《LED前照灯标准》对LED前照灯远光和近光的配光要求,与传统的LED前照灯相比,能耗可降低至原来的75%.  相似文献
8.
研究由MOCVD 技术制备的 GaMnN 外延薄膜光吸收谱.实验发现Mn掺杂后较未掺杂GaN吸收系数在近紫外区增加,在吸收谱低能区144 eV附近观察到吸收峰,吸收系数随Mn浓度的增加而增大.实验结果与基于密度泛函理论的第一性原理计算结果一致,结合理论计算分析认为144 eV附近的吸收峰源于Mn3+离子e态与t2态间的带内跃迁5T25E. 关键词: GaMnN MOCVD 密度泛函理论 光学性质  相似文献
9.
采用基于密度泛函理论(DFT)的第一性原理平面波赝势法(PWP)计算Mg,Si和Mn共掺GaN电子结构和光学性质,分析比较计算结果.计算表明:掺杂后体系均在能隙深处产生自旋极化杂质带,具有半金属性,能产生自旋注入.与Mn掺杂GaN比较,Mg共掺后能使居里温度(TC)升高,并在1.0eV出现源于Mn4+离子基态4T1(F)到4T2关键词: Mg Si和Mn共掺GaN 电子结构 TC)')" href="#">居里温度(TC) 光学性质  相似文献
10.
邢海英  范广涵  周天明 《物理学报》2009,58(5):3324-3330
采用基于密度泛函理论的第一性原理平面波赝势法计算Mg,Zn,Si,O和Mn共掺GaN,分析比较共掺杂后的电子结构和磁学性质,并分别用平均场近似的海森伯模型和Zener理论估算共掺杂后体系的居里温度(TC).计算表明:共掺杂后体系均在能隙深处产生自旋极化杂质带,具有半金属性,能产生自旋注入.p型共掺杂(GaN:Mn-Mg\Zn)后体系具有较GaN:Mn更稳定的FM态且能使TC升高;而n型共掺杂(GaN:Mn-Si\O)后体系FM态稳定性 关键词: Mg Zn Si O和Mn共掺GaN 第一性原理 TC)')" href="#">居里温度(TC)  相似文献
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