Binding energy, electronic states, and optical absorption in a staircase-like spherical quantum dot with hydrogenic impurity

Abstract

In this paper, we compute the impurity binding energy, electronic states, and optical absorption coefficients of a staircaselike spherical quantum dot with on-center hydrogenic impurity within the effective mass approximation. Firstly, we solve the time-independent Schrödinger numerically to obtain the subband energy levels and the wavefunctions of the 1s and 1p states. We then employ these wavefunctions to compute the electron probability densities of the quantum dot with and without the presence of the hydrogenic impurity. Furthermore, we deduce the optical absorption coefficient between 1s and 1p states using the Fermi’s Golden Rule and discuss in detail the effect of geometrical sizes of cores and shells on the transition matrix element, energy level separation, and impurity binding energy. For example, find that an increase in the central core diameter initially blueshifts the optical absorption coefficient and then, redshifts it at higher values whereas an increase in the shell’s thickness causes only blueshifts of the quantum dot absorption. Furthermore, we discuss in detail the effect of the coulomb attraction due to the hydrogenic impurity on the wavefunctions and their overlap. To the best of our knowledge, the present investigation is the first work on the optical properties of a staircase-like spherical quantum dot with on-center hydrogenic impurity. We believe that the manipulation of shells and cores thickness may furnish supplementary advantages in the fabrication of novel generation of electronic devices operating based on inter-subband optical transitions.