共查询到20条相似文献,搜索用时 453 毫秒
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非对称量子阱与系统的本征值和本征函数 总被引:1,自引:0,他引:1
利用薄膜生长技术,通过控制材料的厚度来调整阱宽,控制组分来调整阱深,得到了不同光电特性的超晶格半导体材料。为克服"方形"势阱过于简单和理想的缺点,引入非对称相互作用势来描述组分超晶格量子阱。在量子力学框架内,把电子的Schrodinger方程转化为超几何方程,用系统参数和超几何函数严格地求解了电子的本征值和本征函数,并以Ga1-xAlxAs-GaAs-Ga1-xAlxAs量子阱为例计算了电子的带内跃迁。结果表明,阱内的能级数目和跃迁能量与系统参数有关,适当调节参数可得到不同光电性能的超晶格量子阱。 相似文献
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利用基于密度泛函理论的第一性原理,研究了硫(S)掺杂纤锌矿氧化锌(ZnO)的能带结构、态密度和光学性质。结果表明:掺杂后晶格畸变,晶格常数随着掺杂量的增加而增大;S原子掺杂减小了能带间隙,提高了电子跃迁的概率;进一步的光学性质计算发现,S掺杂后吸收谱出现红移,且吸收谱峰值随掺杂量的增加而增大,提高了可见光和紫外光区域的光吸收。 相似文献
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报道了分子束外延生长80个周期的Al_xGa_(1-x)As/GaAs超晶格,X射线衍射和透射电镜的结果表明超晶格样品有良好的结构特性,光反射光谱观察到阱内的电子跃迁过程,其结果与理论计算相符。 相似文献
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评述了制备纳米级掺杂超晶格材料的MBE技术,给出了材料性能和器件研制结果。从微结构设计出发,研究了平面掺杂GaAs/Al(Ga)As超晶格结构二维电子气有关性质,实验研究取得了重要的进展。 相似文献
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使用飞秒白光泵浦探测技术研究了GaAs/AlGaAs量子阱材料中超快动力学行为。采用了非共振泵浦,激发了不满足△n=2p选择定则的光跃迁,观察到差分透射谱中的3个吸收跃迁饱和漂白峰。一方面,E1导带上的电子和HH2上的空穴通过各种散射和复合而快速减少,E1-HH2和E2-HH2峰迅速衰减;另一方面,由于处在带边的复杂性致使E1-HH1峰在25ps内几乎没有衰减。与掺杂多量阱材料的驰豫动力学比较可知,超晶格中由于阱间波函数的耦合使载流子的散射加快;而掺杂多量子阱中由于捕获中心的存在使载流子的复合加快。 相似文献
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采用分子束外延方法生长了ZnSe-ZnTe应变层超晶格。采用光致发光方法对ZnSe-ZnTe应变层超晶格的光学特性进行了评价,发光颜色为由蓝绿至红的可见光范围内.为了获得宽带Ⅱ-Ⅵ族半导体的p型和n型电导,采用调制掺杂技术制备了ZnSe-ZnTe超晶格,如果在ZnTe层中有选择地掺杂Sb,则所有样品呈现p型电导,且空穴浓度为(0.5-1.0)×10~(14)cm~(-3)。另一方面,Ga掺杂的应变层超晶格的电子浓度为(2-7)×10~(13)cm(-3)。其 相似文献
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正切平方势与量子阱的带内跃迁和带间跃迁 总被引:2,自引:0,他引:2
引入了新的正切平方势来描述量子阱中的电子和空穴运动行为.在量子力学框架内,把粒子的Schr(o)dinger方程化为了超几何方程,并用系统参数和超几何函数严格地求解了粒子的本征值和本征函数,并以Ga1-xAlxAs/GaAs/Ga1-xAlxAs量子阱为例计算了电子和空穴的带内跃迁和带间跃迁.结果表明,电子和空穴在量子阱中的能量是量子化的,而阱内的能级数目和跃迁能量与系统参数有关.于是,可望通过对势阱参数的控制来得到不同光电特性的量子阱材料. 相似文献
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采用k·p方法理论,考虑了极化电场和自由载流子重新分布等因素,通过薛定谔方程和泊松方程自洽求解得到InGaN/AlInGaN,InGaN/GaN,InGaN/InGaN,InGaN/AlGaN量子阱导带和价带的能带结构,并由此计算了不同量子阱结构的自发发射谱.分析对比发现AlInGaN材料特有的自发极化和压电极化效应在阱垒界面处形成的极化电荷对量子阱发光特性有重要的影响.以AlInGaN为垒,优化其中各元素的组分可以减小极化电场的影响,提高量子阱自发发射谱强度.同时,综合考虑了极化电荷和势垒高度的影响,提出了具体的优化方法,并给予了物理解释. 相似文献
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用MOCVD生长发射波长为808nm的ALGaAs/GaAs量子阱激光器材料。通过在激光器材料的波导中加入多量子势垒(MQB)层,有效地限制电子在阱内的复合以及高能电子溢出阱外,从而降低了激光器的阈值电流,提高了它的特征温度。增加了MQB后,器件的阈值电流密度I_(th)从原来的400~600A/cm ̄2下降到300~400A/cm ̄2,特征温度从160K提高到210K。 相似文献
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The energy eigenvalues and eigenfunctions have been obtained for a core-shell CdSe/ZnS quantum dot structure under effective-mass approximation. The electric transition dipole moment is calculated for the 1s-2s electronic transition. The optical nutation signal of the transition of electrons has been calculated numerically based on optical Bloch equations. Particularly, we have investigated the quantum size, the core's radius and the shell's thickness, dependent optical nutation. It is shown from calculation results that the optical nutation signal is sensitive to the size and structure change. And the reasons for the variation of the Rabi frequency have been discussed based on the theory of the quantum size confined effect (QSCE). 相似文献
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By varying the total energy and electrostatic energy functionals which represent an approximate self-consistent solution of Schrödinger's and Poisson's equation, the ground state of electrons is determined in a semiconductor inversion layer. It was assumed that all the electrons in the semiconductor inversion layer are in the ground state.The low frequency capacitance metal-insulator-semiconductor (MIS) capacitors is calculated by the proposed theory and the results are compared with classically calculated capacitance. Numerical results are given for a silicon (111) p-type bulk at 77°K. 相似文献
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Genquan Han Jinzhong Yu Yan Liu 《Photonics Technology Letters, IEEE》2008,20(6):419-421
In this letter, we propose an n-type vertical transition bound-to-continuum Ge-SiGe quantum cascade structure utilizing electronic quantum wells in the L and Gamma valleys of the Ge layers. The optical transition levels are located in the quantum wells in the L valley. Under a bias of 80 kV/cm, the carriers in the lower level are extracted by miniband transport and L -Y tunneling into the subband in the Gamma well of the next period. And then the electrons are injected into the upper level by ultrafast intervalley scattering, which not only effectively increases the tunneling rate and suppresses the thermal backfilling of electrons, but also enhances the injection efficiency of the upper level. The performance of the laser is discussed. 相似文献
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The generation of plasmas in water by high-power laser pulses was investigated for pulse durations between 100 ns and 100 fs on the basis of a rate equation for the free electron density. The rate equation was numerically solved to calculate the evolution of the electron density during the laser pulse and to determine the absorption coefficient and energy density of the plasma. For nanosecond laser pulses, the generation of free electrons in distilled water is initiated by multiphoton ionization but then dominated by cascade ionization. For shorter laser pulses, multiphoton ionization gains ever more importance, and collision and recombination losses during breakdown diminish. The corresponding changes in the evolution of the free carrier density explain the reduction of the energy threshold for breakdown and of the plasma energy density observed with decreasing laser pulse duration. By solving the rate equation, we could also explain the complex pulse duration dependence of plasma transmission found in previous experiments. Good quantitative agreement was found between calculated and measured values for the breakdown threshold, plasma absorption coefficient, and plasma energy density 相似文献
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