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[IEEE 2018 UKSim-AMSS 20th International Conference on Computer Modelling and Simulation (UKSim) - Cambridge, United Kingdom (2018.3.27-2018.3.29)] 2018 UKSim-AMSS 20th International Conference on Computer Modelling and Simulation (UKSim) - A Multiple Quantum Well Structure Simulator
摘要： A simulator was developed for modeling and designing multiple quantum wells structures such as quantum well infrared photodetectors and quantum cascade laser, based on a single-electron effective mass Schr?dinger equation. It employs box integration finite differences and transfer matrix approaches to find energies of bound and scattering states in the structures. The graphical user interface allows the user to vary easily design parameters including effective mass, layer thickness and number of layers as well as simulation parameters in order to optimize the structure for different device applications and functionality. Three simulation examples were performed on: three coupled quantum wells infrared two-color asymmetric quantum well structure, photodetector structure and on a quantum cascade laser design. The results show an accuracy which is comparable to more complicated simulations.
关键词： Effective mass approximation,TMM,Multiple Quantum Wells Structures,FDM
更新于2025-09-23 15:22:29
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Impact of dielectric environment on the linear and nonlinear optical properties for CdS/ZnS cylindrical core/shell quantum dots
摘要： By the mean of the effective mass approximation (E.M.A) and compact density matrix method, the energy eigenvalues, linear and nonlinear dielectric function have been theoretically investigated for CdS/ZnS cylindrical core/shell quantum dot embedded in PVA, PMMA and SiO2 matrices. Simulation results showed that the presence of the dielectric mismatch in the QD-matrix system can lead to a significant enhancement of the nonlinear dielectric function. According to our calculations, peaks of the real and imaginary part of the dielectric function can experience a redshift or a blue shift with the appropriate dielectric environment.
关键词： complex dielectric function,Effective mass approximation,cylindrical core/shell quantum dot,density matrix approach
更新于2025-09-23 15:19:57
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Photoelectric process in GaAs quantum dot
摘要： We study the photoelectric process in single electron charged spherical GaAs/Ga1-yAlyAs quantum dot. The effective mass approximation is used with the finite potential at the dot matrix interface including the effect of self-energy. The total cross section of photoelectric process is investigated with the variation of incident photon energy and the molar concentration y of Al in Ga1-yAlyAs matrix material.
关键词： Quantum dot,Effective mass approximation,Finite potential,Photoelectric process
更新于2025-09-23 15:19:57
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Dielectric environment effect on linear and nonlinear optical properties for CdS/ZnS core/shell quantum dots
摘要： The eigenvalues, transition energy, the linear and nonlinear dielectric functions have been numerically investigated for CdS/ZnS spherical core/shell quantum dots embedded in various dielectric matrices. The evaluation was carried out for three commonly used matrices, such as PVA, PMMA and SiO2. Calculations were done under the effective mass approximation and compact density matrix approach. Results revealed that the nonlinear optical property is strongly affected by the nature of the matrix material. By increasing core/shell radii ratio the energy states as well as the transition energy are decreasing. It is also indicated that the presence of the dielectric mismatch in the QD-matrix system can cause significant enhancement on the linear and third order nonlinear dielectric function.
关键词： Complex dielectric function,Core/shell,Density matrix approach,Effective mass approximation,Nonlinear optic
更新于2025-09-12 10:27:22
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Effects of interface steps on the valley-orbit coupling in a Si/SiGe quantum dot
摘要： Valley-orbit coupling is a key parameter for a silicon quantum dot in determining its suitability for applications in quantum information processing. In this paper we study the effect of interface steps on the magnitude and phase of valley-orbit coupling for an electron in a silicon quantum dot. Within the effective-mass approximation, we ?nd that the location of a step on the interface is important in determining both the magnitude and the phase of the valley-orbit coupling in a Si/SiGe quantum dot. Speci?cally, our numerical results show that the magnitude of valley-orbit coupling can be suppressed up to 75% by a step of one atomic monolayer, and its phase can change by almost π . When two steps are present, the minimum value of the valley-orbit coupling can even approach zero. Our calculation can in principle be generalized to multiple steps as well, as long as the width of the regions between steps is much larger than the atomistic length scale. We also clarify the effects of an applied external magnetic ?eld and the higher orbital states on the valley-orbit coupling. Overall, our results illustrate that interface roughness can strongly affect both the magnitude and the phase of the valley-orbit coupling, which are crucial parameters for both spin and charge qubits in silicon.
关键词： interface steps,silicon quantum dot,effective-mass approximation,quantum information processing,valley-orbit coupling
更新于2025-09-11 14:15:04