  Bistability in quantum dot structures is examined by a drift-diffusion model
in combination with electron capture and emission processes. Our simulations
provide a dynamic scenario with extremely long switching times of the order of
months and the results are in good agreement with the experimental findings of
Yusa and Sakaki [Appl. Phys. Lett. {\bf 70}, 345 (1997)]. The analysis of the
data supports the importance of Auger capture processes for quantum dots.
