Optical Absorption Of A Hydrogenic Impurity In A Disc-shaped Quantum Dot

The impressive progress in the fabrication of low-dimensional semiconductorstructures during the last decade made it possible to reduce the e?ective dimension fromthree dimensional bulk materials, to quasi-two dimensional quantum well systems, toquasi-one dimensional quantum wires, and even to quasi-zero dimensional quantum dots.The quantum confinement e?ects in such semiconductor systems with reduced spacedimensions have attracted considerable attention.Especially interesting are the modifiedelectronic and optical properties of these structures, which are controllable to a certaindegree through the ?exibility in the structure design. This feature makes quantum con-fined semiconductors very promising for possible device applications in microelectronics,nonlinear optics, and many other fields. Therefore, it is urgent for people to understandvarious physical properties of these structures. Research on the optical properties ofquantum dots is more convenient, especially in optical rectification , light absorption andthe refractive index. A large number of studies have shown that the low-dimensionalsemiconductor materials is very good, one of the non-linear optical materials. Withthe system of reduced size and dimension, and its nonlinear optical properties will bemore obvious and more extensive range of applications. Therefore, the low-dimensionalsemiconductor quantum dots of the nonlinear optical e?ect has become an important ele-ment in the research field of nonlinear optics. Composed by the five chapters of this thesis.In the first chapter, the general characters§development history and applications oflow dimensional semiconductor structures and the system of disc-shaped quantum dothave been summarized brie?y.In the second chapter, we mainly study the impurity state of disc-shaped quantumdots by using the perturbation methods. Within the framework of e?ective-massapproximation, we discuss the levels of the impurity state, and analyze it to know thatthe confinement e?ect on the levels of the impurity state by perturbation methods.Then we study the binding energy,the oscillator strength and the linear and nonlinearabsorption coe?cient based on the computed energies and wave functions.In the third chapter,by using the expression of the eigenfunction and the linearand the third-order nonlinear absorption coe?cient, which obtained by chapter two. we mainly study the e?ects of the hydrostatic pressure and temperature on the opticalproperties of a hydrogenic impurity in the disc-shaped quantum dot.In the last chapter, summary of the paper and the main results are given; theshortage and further research are also mentioned.