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 Schrodinger equation is reduced to a one-dimensional equation with an effective potential containing both the Coulomb interaction and the effects of the wire surface irregularities through the boundary conditions; Studying the ground-state wave functions for different positions of the impurity along the wire axis, we have found that there are wire deformation geometries for which 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 impurities along the wire axis leads to a ladder of energy states spanning an interval of about 0.290 eV.