Donor impurity related optical and electronic properties of cylindrical GaAs-AlxGa1−x As quantum dots under tilted electric and magnetic fields

Abstract

AbstractThis article makes a theoretical study of the optical and electronic properties in cylindrical GaAs-Alx Ga1−x As quantum dots in the presence of an arbitrarily located donor impurity and considering the simultaneous effects of tilted electric and magnetic fields. The studies are developed in the effective mass and parabolic band approximations. The solution of the Schrödinger equation is done through the finite element method considering tetrahedral meshes that can be adapted to regions where there are abrupt variations of the materials that make up the structure. Among the many results, reported for the first time in this article, we can mention: (i) the electronic spectrum, without and with shallow donor impurity, considering separate and combined effects of tilted electric and magnetic fields, (ii) the ground state binding energy as a function of the external electric and magnetic fields, their orientations concerning the axial axis of the quantum dot, and the impurity position, (iii) the squared reduced dipole matrix elements for impurity related inter-level optical transitions as a function of the tilted electric and magnetic fields and impurity position, and (iv) the optical absorption coefficient between the ground state and at least the first fifteen lowest excited states under tilted electric and magnetic fields and considering several impurity positions. From this study it can be concluded that the presence of tilted electric and magnetic fields and on-center or off-center shallow donor impurities, ostensibly enrich the optical and electronic properties of the system. It is observed that due to the rupture of the azimuthal symmetry of the cylindrical quantum dot, important modifications of the selection rules for inter-level transitions between states appear.