Electron trapping in quantum-well structures

The trapping of electrons by charged impurities or holes in quantum wells and bulk semiconductors is investigated using a theory of encounter dynamics which can be applied for the arbitrary mean free path of the carriers. The theory reduces the dimensionality d of the encounter problem from two dimensions (quantum wells) or three dimensions (bulk semiconductors) to a one-dimensional problem of passage over a barrier in the effective potential V(R)-(d-1)kT lnR, where V(R) is the screened Coulomb potential. The results show that the effect of the reduced configuration space available in two dimensions is a lower encounter rate.