Bo Hellsing | PubMed Health

PubMed2004

Surface relaxation influenced by surface states.

A detailed theoretical investigation of the relaxation of the simple metal surface Al(100) is presented. We show the influence of electronic surface states in this context. The sign and magnitude of the relaxation of the topmost atomic layers is mainly determined by the rearrangements of the surface state charge. The degree of surface relaxation convergence, with respect to the number of slab layers, is determined by the location of the surface state band relative to bulk bands.

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PubMed2003

An interfacial complex in ZnO and its influence on charge transport.

The segregation of native defects and Bi impurities to a high-angle grain boundary in ZnO is studied by first-principles calculations. It is found that the presence of Bi(Zn) increases the concentration of native defects of acceptor type in the grain boundary. This leads to the formation of a Bi(Zn)+V(Zn)+O(i) interfacial complex under O-rich conditions and exhibits a localized acceptor state. This state, which is different from that of the isolated impurity, gives the grain boundary p-type character and when embedded between n-type ZnO grains is consistent with the double Schottky barrier model for Bi-doped ZnO varistors.

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