金量子点阵列在有序二氧化硅介孔薄膜中的束缚研究

Periodic disposed quantum dot arrays are very useful for the large scale integration of single electron devices. Gold quantum dot arrays were self-assembled inside pore channels of ordered amino-functionalized mesoporous silica thin films, employing the neutralization reaction between chloroauric acid and amino groups. The diameters of quantum dots are controlled via changing the aperture of pore channels from 2.3 to 8.3 nm, which are characterized by HRTEM, SEM and FT-IR. UV-vis absorption spectra of gold nanoparticle/mesoporous silica composite thin films exhibit a blue shift and intensity drop of the absorption peak as the aperture of mesopores decreases, which represents the energy level change of quantum dot arrays due to the quantum size effect.     

Anisotropic transport properties of quantum dot arrays fabricated by the edge-defined nanowires

The anisotropic transport properties of quantum dot arrays fabricated by the nanoimprinted multilayer quantum wires have been investigated. The vertical transport characteristics are estimated by the carrier capture time from the electron reservoir to the low dimensional structures, which turned out to be longer than the spontaneous emission lifetime. The lateral transport characteristics are modeled after the quantum conductance between quantum dot arrays which are readily available from the miniband structures. The resulting lateral transport revealed that lateral quantum conductance can be minimized when the Fermi level is kept at the center of the miniband gap when the gap is larger than 4 kT.     

量子点阵列光致荧光谱温度依赖性研究

多模量子点阵列的光致荧光(PL)光谱的温度依赖性研究对于实现高效的量子点光电器件有着非常重要的意义.利用速率方程模型模拟不同密度量子点阵列中的载流子动力学过程.研究表明,高密度量子点阵列中不同尺寸量子点族的PL强度表现不同的温度依赖关系;而低密度量子点阵列不同点族PL强度均随温度衰减.高密度量子点阵列中,载流子被热激发到浸润层后,部分地被大量子点再俘获,即在量子点族间转移;低密度量子点阵列中不同量子点族间的载流子转移受到限制.不同量子点族光致荧光强度比的最大值强烈地依赖于量子点的激活能差.     

微腔中量子点光子发射的动力学研究

基于量子回归理论建立了微腔-量子点耦合模型的主方程,研究了用激光脉冲激发时微腔中的量子点二能级系统的密度矩阵随时间的演化,然后通过密度矩阵得出发射光子数和二阶相关度等特性,并对适合于制作单光子源的微腔参数和泵浦条件进行了优化。相关参数中,微腔衰退率和系统耦合系数的相对关系对单光子发射过程起关键作用。     

Investigation of carrier relaxation dynamics in single CdSe/ZnSe self-organized quantum dot by time-resolved micro-photoluminescence

We have investigated carrier relaxation dynamics in single CdSe/ZnSe quantum dot (QD) by time-resolved micro-photoluminescence (PL). The discrete sharp lines, originated from individual QD states, exhibit various rise and decay time constants. The decay times of the sharp lines from ground states and excited states are estimated to be 700≈800 psec and 400≈500 psec, respectively, and the rise times of the ground states become longer compared with those of the excited states. There results are in contrast to successive change of the rise and decay times observed in time-resolved macro-PL with varying the detection wave-length. The quasi-continuum higher states with much shorter decay times are clearly observed over the discrete states of the QDs.     

一维量子点阵列的自旋链上信息传输

基于紧束缚模型的实空间格点组成的一维线性均匀有序的量子点阵列为研究对象,然后利用演化算符的作用使其在量子点阵列的自旋链上进行单量子比特的信息传输。即使用演化算符 使单比特量子态从量子点阵列起始端为多粒子态 传输到末端态为 ,最后在此基础上计算概率来讨论了单量子比特能从起始端的多粒子态 的第一个量子比特完全传输到态 的末端第N个量子比特是可能的。     

Rashba效应下量子点中束缚极化子的有效质量

采用线性组合算符、LLP幺正变换和变分方法,研究Rashba效应下量子点中强耦合束缚极化子有效质量的性质。对RbCl量子点数值计算的结果表明：极化子的振动频率、有效质量均随极化子速率、受限强度和库仑束缚势的增大而增大,原因是极化子速率增大电子动能增加,库仑束缚势增大导致电子-声子间相互作用增强,受限强度增大使电子运动的有效范围减小导致电子能量增大,进而使极化子的振动频率和有效质量增大。受Rashba自旋轨道相互作用的影响,极化子的有效质量发生劈裂,劈裂间距随极化子速率的增大而减小。     

量子点异质结中类氢杂质电子束缚能级的计算

采用球壳结构和渐变有限深谐振子势阱模型,利用镜像电荷的方法分析了不同介电常数下,界面效应对半导体量子点异质结中类氢杂质电子束缚能级的扰动情况.通过计算考虑到杂质对电子的束缚作用前后的电子的基态能,可以看出对于处在弱受限情况下的量子点,异质结厚度在小于10 nm时,界面效应对类氢杂质电子束缚能级的影响明显.当异质结壳层厚度增大的时候,界面效应的影响将逐渐减弱,受扰动的基态能也逐渐减小,最后不同Airy函数零点值所对应的基态能趋向于某一固定值,此时界面效应可以忽略.     

配体链长对PbS量子点薄膜/Al肖特基结整流特性的影响

利用热注入法合成带有油酸配体的PbS量子点, 用短链乙醇胺替代长链油酸做为PbS量 子点的配体。 对比了由两种材料制得的量子点薄膜与Al形成的肖特基结的J-V特性,采用热 电子发射理论对其J-V特 性进行分析,结果发现,接有短链乙醇胺的PbS量子点薄膜具有更优的整流特 性,理想因子n为3.8,明显低 于采用油酸配体的PbS量子点(n=4.6)。 研究表明,短链配体有利于提高PbS薄膜表面的均匀性并形成较好的肖 特基接触;短链置换过程提高了量子点薄膜与Al电极的接触势垒高度,使肖特基结反向 漏电流降低。