  We carry out a detailed investigation of neutral ($D^0$) 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 $D^0$ and
$D^-$. Further, our study of the optical gaps also reveals a {\textbf{SHADES}}
transition.
