Doping as a self-regulating phenomena

Titolo: Doping as a self-regulating phenomena

Relatore: Prof. Alex Zunger (University of Colorado, Boulder)

Coordinate: venerdì 1 luglio, ore 10:30, aula E

Abstract: Materials that cannot be doped to create mobile-carriers are useless for a wide range of (transport-based) device technologies. Yet, many insulators cannot be doped at all i.e. introducing carriers does not create conductivity and/or does not shift the Fermi energy.  Those insulators that can be doped can often be doped either by electron  (e.g. ZnO) o by holes   (e.g. NiO, Diamond), but not both. Such doping trends are often viewed in the literature as temporary and accidental setback –limitations that would soon be overcome by a better crystal grower.
 Analysis of doping using first principles methods suggests otherwise—that equilibrium doping is a ‘genetic’ tendency of the host solid, not an accident, and that it reflects different   tendencies by different materials to develop ‘anti-bodies’ to doping. Such a self-regulating (Le Chatelier like) effect constitutes a deeper understanding of a broad range of doping phenomenology.