InGaAs/GaAs应变量子阱结构在1054nm激光器中的应用

采用金属有机物化学气相淀积(MOCVD)方法生长了InGaAs/GaAs应变量子阱,通过优化生长条件和采用应变缓冲层结构获得量子阱,将该量子阱结构应用于1 054 nm激光器的制备。经测试该器件具有9 mA低阈值电流和0.4 W/A较高的单面斜率效率,在驱动电流为50 mA时测得该应变量子阱光谱半宽为1.6nm,发射波长为1 054 nm。实验表明:通过优化工艺条件和采用应变缓冲层等手段,改善了应变量子阱质量,该结果应用于1 054 nm激光器的制备,取得了较好的结果。     

三嵌段共聚物的电子结构及态密度特征

采用紧束缚近似计算方法,针对小带隙的聚乙炔(polyacetylene,(PA))和大带隙的聚对苯撑(poly(p-phenylene),(PPP)组成的三嵌段共聚物(triblock copolymer)-(PA)x-(PPP)n-(PA)y-和-(PPP)x-(PA)n-(PPP)y-性质进行了研究,发现它们具有典型的量子阱特征.对均聚物PPP和PA以及三嵌段共聚物的态密度(density of states, (DOS))进行了计算分析,发现共聚物的态密度与均聚物的态密度有着显著的区别,共聚物的带隙的大小介于大带隙的PPP和小带隙的PA之间,在共聚物中与PPP的导带和价带的子带隙以及共聚物的导带底和价带顶中,所存在的能态密度只能由PA来提供,而在共聚物的价带底和导带顶的能态密度则取决于PPP的态密度.     

有机量子阱电致发光器件

制备了普通的有机量子阱结构,并对结构进行了表征.在此基础上,制备了量子阱结构的白光电致发光器件.在分析了制作工艺对有机量子阱结构特性可能产生的影响之后,为了减少垒、阱界面互扩散效应的影响,提出了有机掺杂量子阱的概念,即垒与阱的母体是相同材料,只是在生长垒层的过程中同时掺入少量发光剂.由于掺杂剂的浓度梯度只有百分之零点几,因此,界面互扩散的影响很小,实际上我们用这种办法制备的有机量子阱器件的亮度、效率均有明显提高.在研究了阱数对器件特性的影响之后,我们发现一般情况下,两个阱是最好的.进一步研究了阱母体材料对有机量子阱器件特性的影响,结果发现,用NPB作母体比Alq作母体更好,这时器件的效率(cd/A)在45～13V工作电压范围内变化不大.     

Polar Oscillation of Interface and Surface Optical Phonons in Free-Standing Cylindrical Quantum-Well Wires

Under dielectric continuum approximation, interface optical (IO) and surface optical (SO) phonon modes as well as the corresponding Fro^ehlich electron-phonon interaction Hamiltonian in a free-standing cylindrical quantum-well wire (QWW) are derived and studied. Numerical calculations on GaAs/AlzGa1-x As cylindrical QWW are performed. Results reveal that there are two branches of IO phonon modes and one branch of SO phonon mode, and the dispersion frequencies of IO or SO phonon modes sensitively depend on the Al mole fraction x in AlzGa1-x As material and the wavevector in z direction, kz. With the increasing of kz and quantum number m, the frequency of each IO mode approaches one of the two frequency values of the single GaAs/AlxGa1-x As heterostructure, and the electrostatic potential distribution of the phonon mode tends to be more and more localized at a certain interface or surface, meanwhile, the coupling between the electron-IO and -SO phonons becomes weaker.     

电场对量子阱中强耦合磁极化子性质的影响

研究了量子阱中强耦合磁极化子在电场作用下的性质,采用线性组合算符及幺正变换的方法导出了强耦合磁极化子的振动频率λ和基态能量E₀.讨论了强耦合磁极化子的基态能量与阱宽、电场强度、回旋频率之间的关系.通过数值计算,结果表明:强耦合磁极化子的基态能量的绝对值随着阱宽的增加而减小,随着外加电场强度的增加而增加;磁极化子的基态能量的绝对值随着磁场的回旋频率的增加而增加;磁场的回旋频率随着磁极化子的振动频率的增加而增加.     

Quantum correlations and optical effects in a quantum-well cavity with a second-order nonlinearity

In this paper, we investigate the photon correlations and the statistical properties of light produced by an optical cavity with an embedded quantum well interacting with squeezed light. We show that the squeezed source substantially improves the intensity of the emitted light and generates a narrowing and a duplication of the spectrum peaks. With a strong dependence on frequency detuning, the cavity produces considerably squeezed radiation, and perfect squeezing is predicted for weak light–matter interactions. Furthermore, the system under consideration presents a bunching effect of the transmitted radiation resulting from weak pumping of the coherent field. The results obtained may have potential applications in the fields of very accurate measurement and quantum computing.     

多晶SiGe栅量子阱pMOSFET阈值电压模型

本文基于多晶SiGe栅量子阱SiGe pMOSFET器件物理,考虑沟道反型时自由载流子对器件纵向电势的影响,通过求解泊松方程,建立了p+多晶SiGe栅量子阱沟道pMOS阈值电压和表面寄生沟道开启电压模型.应用MATLAB对该器件模型进行了数值分析,讨论了多晶Si_1-yGe_y栅Ge组分、Si_1-xGe_x量子阱沟道Ge组分、栅氧化层厚度、Si帽层厚度、沟道区掺杂浓度和 关键词： 多晶SiGe栅 寄生沟道 量子阱沟道 阈值电压     

Influence of Nonlinear Refraction on the Spectral Characteristics of GaAlAs/GaAs Lasers

Numerical modeling of the spectral characteristics of single-frequency lasers is carried out by using a model which takes into account nonlinear refraction. It is shown that account for nonlinear refraction allows one to obtain satisfactory coincidence of the experimental and theoretical spectral characteristics of quantum-well lasers.     

Near-infrared tunable narrow filter properties in a 1D photonic crystal containing semiconductor metamaterial photonic quantum-well defect

The near-infrared (NIR) narrow filter properties in the transmission spectra of a one-dimensional photonic crystal doped with semiconductor metamaterial photonic quantum-well defect (PQW) were theoretically studied. The behavior of the defect mode as a function of the stack number of the PQW defect structure, the filling factor of semiconductor metamaterial layer, the polarization and the angle of incidence were investigated for Al-doped ZnO (AZO) and ZnO as the semiconductor metamaterial layer. It is found that the frequency of the defect mode can be tuned by variation of the period of the defect structure, polarization, incidence angle, and the filling factor of the semiconductor metamaterial layer. It is also shown that the number of the defect mode is independent of the period of the PQW defect structure and is in sharp contrast with the case where a common dielectric or metamaterial defect are used. The results also show that for both polarizations the defect mode is red-shifted as the number of the defect period and filling factor increase. An opposite trend is observed as the angle of incidence increases. The proposed structure could provide useful information for designing new types of tuneable narrowband filters at NIR region.     

Properties of Excitons Bound to Neutral Donors in GaAs-AlxGa1-xAs Quantum-Well Wires

In the effective-mass approximation, using a simple two-parameter wave function and a one-dimensional (1D) equivalent potential model, we calculate variationally the binding energy of an exciton bound to a neutral donor (D⁰,X) in finite GaAs-Al_xGa_1-xAs quantum well wires (QWWs). At the wire width of 25 Å, the binding energy has a peak value, which is also at the position of the peak of the exciton binding energy, and the center-of-mass wave functions of excitons reaches the most centralized distribution. In addition, the changing tendency of the average interparticle distance as the wire width is reverse to that of the binding energy.