Theoretical calculations of shallow impurity states in deformed quantum wires with an application to porous silicon

We present results on the ground-state binding energies for donor (acceptor ) impurities in a deformed quantum wire. The impurity effective-mass Schrod inger equation is reduced to a one-dimensional equation with an effective p otential containing both the Coulomb interaction and the effects of the wir e surface irregularities through the boundary conditions; Studying the grou nd-state wave functions for different positions of the impurity along the w ire axis, we have found that there are wire deformation geometries for whic h the impurity wave function is localized either on the wire deformation or on the impurity, or even on both. With the wire geometries compatible with the light emission in porous silicon, we show that a distribution of impur ities along the wire axis leads to a ladder of energy states spanning an in terval of about 0.290 eV.