We carry out a detailed investigation of neutral (D0) and charged (D−) impurity states of hydrogen-like donors in spherical semiconductor quantum dots. The investigation is carried out within the effective mass theory (EMT). We take recourse to local density approximation (LDA) and the Harbola-Sahni (HS) schemes for treating many-body effects. We experiment with a variety of confining potentials: square, harmonic and triangular. We observe that the donor level undergoes shallow to deep transition as the dot radius (R) is reduced. On further reduction of the dot radius it becomes shallow again. We term this non-monotonic behaviour \textbf{SHADES}. This suggests the possibility of carrier {\textbf{\textit{``freeze out''}}} for both D0 and D−. Further, our study of the optical gaps also reveals a {\textbf{SHADES}} transition.
@article{arxiv.cond-mat/0308029,
title = {Shallow Deep Transitions of Neutral and Charged Donor States in Semiconductor Quantum Dots},
author = {R. K. Pandey and Manoj K. Harbola and Vijay A. Singh},
journal= {arXiv preprint arXiv:cond-mat/0308029},
year = {2009}
}