  We investigate the dynamics of impurities walking along a semiconductor layer
assisted by thermal noise of strength $D$ and external harmonic potential
$V(x)$. Applying a nonhomogeneous hot temperature in the vicinity of the
potential minimum may modify the external potential into a bistable effective
potential.
  We propose the ways of mobilizing and eradicating the unwanted impurities
along the semiconductor layer. Furthermore, the thermally activated rate of
hopping for the impurities as a function of the model parameters is studied in
high barrier limit. Via two state approximation, we also study the stochastic
resonance (SR) of the impurities dynamics where the same noise source that
induces the dynamics also induces the transition from mono-stable to bistable
state which leads to SR in the presence of time varying field.
