Electronic States In Low-dimensional Semiconductor Nanostructures

With the development of the crystal growth technology,more and more experimental and theoretical works have been devoted to the study of the properties of impurity states in low-dimensional semiconductor structures,such as two-dimensional quantum-wells(QWs), one-dimensional quantum-well wires(QWWs),and zero-dimensional quantum dots(QDs), which has become a remarkable new field.The low-dimensional semiconductor structures have attracted increasing attention for potential application on new electronic devices.In this article we study the electron states in low-dimension semiconductor structures in the framework of effective-mass envelope-function theory using the plane wave method.The main contents are presented as following:1.The concept and the main kinds of low-dimensional semiconductor materials are introduced systematically.The main theoretical research methods and the application are also discussed.2.The shallow hydrogenic donor impurity states in square,V-shaped,and parabolic quantum wells are studied in the framework of effective-mass envelope-function theory using the plane wave basis.The calculation results indicate that impurity energy levels decrease with the increase of the well width and decrease quickly when the well width is small.The binding energy of the ground state increases until it reaches a maximum value,and then decreases as the well width increases.3.External electric field effect on the hydrogenic donor impurity in zinc-blende InGaN quantum well wire(QWW) is studied.It is shown that the donor binding energy is highly dependent on the impurity position,the radius of the QWW and the external electric field.In addition,Stark shift dependence on the radius of the QWW and the external electric field is calculated.The donor binding energy has a maximum when the impurity located at the center of the QWW.The donor binding energy decreases with the increase of the external electric field, but stark shift increases with the increase of the external electric field or the radius of the QWW.4.The external electric field effect on binding energy of a hydrogenic donor impurity in zinc-blende(ZB) InGaN QD is discussed.It is shown that the donor binding energy is highly dependent on the impurity position,QD size and the external electric field.The symmetry of the electron probability distribution is broken and the maximum of the donor binding energy is shifted from the center of QD in the presence of the external electric field.The energy levels are split and the splitting increases with the increase of QD height.The splitting increases up to a maximum and then decreases with the increase of QD radius.