Density of impurity states in doped spherical quantum dots

Abstract

We analyze the electronic states in spherical quantum dots (SQDs) with randomly distributed neutral, D0 and negatively charged D− donors by using the recently developed fractal dimension method, in which the problems of the D0 and the D− are reduced to similar ones for a hydrogen-like atom and a negative-hydrogen-like ion, respectively, in an isotropic effective space with the fractal dimension which depends on the electron–ion donor separation. In order to solve these problems in the new effective space, we use the numerical trigonometric sweep method and the three-parameter Hylleraas trial function. We present novel curves for the density of D0 impurity states for different potentials with and without the repulsive core. We find that the curves of the density of states with repulsive core have additional peaks, whose position and intensity depends on the width and the height barrier at the center of the dot. Our results are in a good agreement with those obtained previously for donor spectra in SQD with square-well potential shape.