等腰直角三角柱形量子点的能级结构和波函数

采用分离变量法和无限深势阱模型求解了等腰直角三角柱形量子点的能级结构和波函数。给出了能级结构和波函数的表达式，并绘制了前几个本征波函数的等值线。对直角边长5nm，高度5nm的等腰直角三角柱形量子点，其能级的最小值为 。结论可以用于量子计算或量子通信中，如使用一个截面为正方形的柱形结构来存储两个或四个量子信息。也可以用于导波光学中，如用一个正方形的导波结构传输两路或四路光信号。     

等腰直角三角柱形量子点的能级结构和波函数

采用分离变量法和无限深势阱模型求解了等腰直角三角柱形量子点的能级结构和波函数.给出了能级结构和波函数的表达式,并绘制了前几个本征波函数的等值线.对直角边长5 nm,高度5 nm的等腰直角三角柱形量子点,其能级的最小值为E=0.09209 eV.结论可以用于量子计算或量子通信中,如使用一个截面为正方形的柱形结构来存储两个或四个量子信息.也可以用于导波光学中,如用一个正方形的导波结构传输两路或四路光信号.     

耦合量子点中空穴基态反键态特性研究

本文采用六带K·P理论计算了耦合量子点在不同耦合距离下空穴基态特性, 探讨了轻重空穴及轨道自旋相互作用对耦合量子点空穴基态反成键态特性的影响. 在考虑多带耦合的情况下, 耦合量子点随着耦合强度的变化, 价带基态能级和激发态能级发生反交叉现象. 同时, 随着耦合距离的增加, 量子点基态轻重空穴波函数的比重发生变化,导致量子点空穴基态波函数从成键态反转成为反成键态. 同时研究发现, 因空穴基态及激发态波函数特性的转变, 电子、空穴的基态及激发态波函数的叠加强度发生的明显变化. 关键词： 耦合量子点 反键态 多带理论 自旋轨道耦合     

纤锌矿GaN柱形量子点中类氢施主杂质态

在有效质量近似和变分原理的基础上,选取含两个变分参数的波函数,研究了纤锌矿结构的GaN/AlxGa1-xN单量子点中类氢施主杂质体系的结合能随量子点(QD)尺寸以及杂质在量子点中位置的变化,并与以前使用不同尝试波函数的计算结果进行了比较。结果表明:由我们选取的两变分参数波函数得到的结果与前人选取的两变分参数波函数得到的结果相比有所改进,而与选取一个变分参数波函数得到的结果一致。同时我们还计算了体系的维里定理值随量子点半径的变化情况,所得结果与前人工作结果一致,说明本文选取的两变分参数波函数能很好地描述柱形量子点中施主杂质态的运动。     

耦合锗量子点中空穴态对称特性研究

分别采用单带重空穴近似和六带Kronig-Penney模型, 对垂直耦合锗量子点在不同耦合距离下的空穴态特性进行了计算, 并探讨了自旋-轨道的相互作用对空穴态对称性的影响. 计算结果表明: 多带耦合的框架下, 随着量子点垂直间距的增大, 空穴基态从成键态转变为反键态, 而且价带基态能级和第一激发态能级发生反交叉现象, 这与单带模型下得到的相应结果存在较大差异. 通过分析六带模型计算得到的成、反键态波函数, 轻、重空穴态和自旋-轨道分裂态对特征空穴态波函数的贡献比例随着量子点垂直间距的增大发生了转变, 并最终导致量子点空穴基态波函数由成键态转变为反键态. 关键词： 耦合量子点 空穴态 成健态-反健态 自旋-轨道     

无限深势阱下杂质量子点的能级计算

在有效质量近似下,垂直方向采用无限深势阱限制势,在x-y平面上,量子点内采用抛物势近似,在量子点边界处采用与实际情况更接近的无限深势阱.在中心杂质电荷为ηe时,利用波函数近似,得到基态和低激发态的能级,与x-y平面均采用抛物势时得到的能级进行了比较.计算发现在量子点真实半径比较小时,电子的基态和低激发态受其影响很大,而相应的能级随量子点的半径逐步增大.在量子点半径大于5倍有效玻尔半径时,能级受其影响已经变得很弱.并且,随着磁场的变化,量子点半径对基态和第一激发态的能级差的影响也很大.最后我们计算了杂质电子的基态束缚能并讨论了声子对其影响.     

电子在圆柱形半导体量子线中的行为研究

用计算一维势阱波函数的方法简化了圆柱形量子线波函数的计算, 得出了量子线中电子的能态、 能级图和波函数。 在确定温度条件下, 讨论了量子线的线宽与它的光谱蓝移、 能级分离或兼并以及电子能态的关系。The wave function of column quantum wires has been calculated with the means of calculation for the quantum wave function in one dimensional potential well. The energy state, energy level diagram and wave function of column quantum wire have gained. Under assured temperature, the relations of column quantum wire diameter to its spectrum blue shift, separation or annexation of energy level, and electrons energy state have been discussed.     

用点正则变换方法求解双原子分子的双曲型Poschl-Teller势的束缚态

采用在点正则变换下形状不变势的映射方法,给出了将Poschl-Teller Ⅰ势映射至Poschl-Teller Ⅱ势的点正则变换,并从Poschl-TellerI势的束缚态能级和波函数求得了Poschl-Teller Ⅱ势的束缚态能级和波函数.     

(nc-Si/SiO2)/SiO2多层量子点结构的激子能级

采用球型量子点模型,应用有效质量近似理论,研究了(nc-Si/SiO2)/SiO2多层量子点结构的激子能级和波函数.结果表明,有限深势阱模型的引入更符合实际更加准确.无论在无限深或有限深势阱下,激子质心运动部分基态能量随最子点半径的减小而急剧增大.对于相同的量子点半径α,无限深势阱下的质心部分能量总比有限深势阱高,且二者的差距随α的减小小而增大.     

用点正则变换方法求解双原子分子的双曲型P?schl-Teller势的束缚态

采用在点正则变换下形状不变势的映射方法,给出了将Poschl-Teller Ⅰ势映射至Poschl-Teller Ⅱ势的点正则变换,并从Poschl-TellerI势的束缚态能级和波函数求得了Poschl-Teller Ⅱ势的束缚态能级和波函数.     

Electronic states in the valence band of a cylindrical ZnSe quantum dot

Electronic states in the valence band of a cylindrical ZnSe quantum dot are studied with allowance for the valence band mixing. Dependences of the wave functions and energy levels on the quantum dot radius are calculated. The influence of a magnetic field parallel to the quantum dot radius on the energy levels is also considered.     

Thermodynamic and kinetic properties of phonons in cylindrical quantum dots

The Green's function technique, suitable for analyses of spatially deformed structures, is developed in this paper and applied to phonon system. The thermodynamic and kinetic phonon properties of cylindrical quantum dots are analysed using a developed method. As a consequence of the applied new method the configurational dependence of diffusion coefficient and dot's density were included into calculations. Maximum of diffusion and minimum of density is located in central part of the cylindrical quantum dot. All thermodynamic and kinetic characteristics of quantum dot are exponentially small at low temperatures. The low phonons specific heat as well as the low thermal conductivity lead to conclusion that in cylindrical quantum dots exist more convenient conditions for appearance of electron superconductivity.     

Impurity states in a cylindrical quantum dot with the modified Pöschl-Teller potential

We study impurity states in a cylindrical quantum dot with two confining potentials: in the direction of cylinder axis modified Pöschl-Teller potential and in radial direction parabolic potential. Studies of impurity states are performed in the frames of variational method and by using numerical methods, the dependences of the particle energy on the geometrical parameters of the cylindrical quantum dot are derived. Dependences of the electron binding energy on the half-width and depth of the potential wall are revealed.     

柱形量子点中的三阶极化率

利用量子力学的密度矩阵理论,在有效质量近似下，采用有限深势阱模型，导出了柱形量子点的三阶非线性极化率的解析表达式.通过数值计算，分析了GaAs/AlβGa1－βAs柱形量子点的三阶非线性极化率与量子点尺寸、掺杂浓度、入射光的频率和偏振方向等参量的关系.结果表明，三阶极化率峰值位置与这些参量密切相关，并且对于确定频率和偏振方向的入射光以及材料的掺杂浓度，存在与之相匹配的量子点尺寸，使三阶极化率达到极大，比体材料的相应值高出2个数量级以上.     

纤锌矿GaN/AlxGa1-xN应变柱形量子点中杂质态结合能及其压力效应

考虑应变及流体静压力,在有效质量近似下,利用变分法计算了无限高GaN/Al<,x>Ga<,1-x>N应变柱形量子点中类氢杂质结合能.结果表明,在量子点尺寸较小情况下,应变增加了杂质态结合能;而在量子点尺寸较大情况下,应变降低了杂质态结合能.随着Al摩尔分数的增加,杂质态结合能减小.杂质态结合能随着流体静压力的增加而增大...     

Vibration Spectrums of Polar Interface Optical Phonons in GaAs/AlAs Cylindrical Quantum Dots

The dispersions of the top interface optical phonons and the side interface optical phonons in cylindrical quantum dots are solved by using the dielectric continuum model. Our calculation mainly focuses on the frequency dependence of the IO phonon modes on the wave-vector and quantum number in the cylindrical quantum dot system. Results reveal that the frequency of top interface optical phonon sensitively depends on the discrete wave-vector in z direction and the azimuthal quantum number, while that of the side interface optical phonon mode depends on the radial and azimuthal quantum numbers. These features are obviously different from those in quantum well, quantum well wire, and spherical quantum dot systems. The limited frequencies of interface optical modes for the large wave-vector or quantum number approach two certain constant values, and the math and physical reasons for this feature have been explained reasonably.     

Energy transfer in hybrid systems quantum dot–plasmonic nanostructures

Radiationless relaxation in hybrid systems quantum dot (QD)–plasmonic nanostructure is considered. For the system QD–2D plasma the relaxation rate extremely steeply depends on the radius of quantum dot while in the pair QD–cylindrical wire contacting each other this dependence is logarithmic weak.     

柱形量子点中弱耦合磁极化子的性质

应用线性组合算符方法和幺正变换方法,研究在抛物势作用下的柱形量子点中磁极化子的性质。对ZnS量子点的数值计算表明,量子点中磁极化子的基态能量随特征频率、回旋共振频率的增大而增加,这是由于特征频率增加时振动能量、回旋共振频率增加时外磁场中的附加能量增加所致。当特征频率(或回旋共振频率)增加到某一值时,磁极化子能量由负变为正。基态能量随柱高的减小而增加,且柱高越小,增加越快;当柱高减小到某一值时,磁极化子能量也由负变为正。总之,柱形量子点中的磁极化子,其基态能量与量子点的尺度、外磁场、特征频率等有关。     

Exciton-phonon interaction in cylindrical semiconductor quantum dots

The exciton-longitudinal optical phonon interaction is theoretically investigated for the case of polar semiconductor cylindrical quantum dots embedded in semiconductor matrix. The theory is developed within the dielectric continuum model considering the Fröhlich interaction between electrons and confined bulk longitudinal optical phonons for a configurational interaction model of quantum dot. Representative longitudinal optical phonon mode for the exciton-phonon interaction is predicted for cylindrical InAs/GaAs quantum dots.     

Radiative life time of an exciton confined in a strained GaN/Ga1-xAlxN cylindrical dot: built-in electric field effects

The binding energy of an exciton in a wurtzite GaN/GaAlN strained cylindrical quantum dot is investigated theoretically.The strong built-in electric field due to the spontaneous and piezoelectric polarizations of a GaN/GaAlN quantum dot is included.Numerical calculations are performed using a variational procedure within the single band effective mass approximation.Valence-band anisotropy is included in our theoretical model by using different hole masses in different spatial directions.The exciton oscillator strength and the exciton lifetime for radiative recombination each as a function of dot radius have been computed.The result elucidates that the strong built-in electric field influences the oscillator strength and the recombination life time of the exciton.It is observed that the ground state exciton binding energy and the interband emission energy increase when the cylindrical quantum dot height or radius is decreased,and that the exciton binding energy,the oscillator strength and the radiative lifetime each as a function of structural parameters (height and radius) sensitively depend on the strong built-in electric field.The obtained results are useful for the design of some opto-photoelectronic devices.