Electronic structure calculations for Au-doped Ge and Si with a possible high thermoelectric power

Citation
K. Fukushima et N. Kondo, Electronic structure calculations for Au-doped Ge and Si with a possible high thermoelectric power, JPN J A P 1, 40(5A), 2001, pp. 3226-3230
Citations number
10
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science
Volume
40
Issue
5A
Year of publication
2001
Pages
3226 - 3230
Database
ISI
SICI code
0021-4922(200105)40:5A<3226:ESCFAG>2.0.ZU;2-M
Abstract
Molecular orbital calculations were performed to investigate electronic str uctures of gold-doped germanium and silicon with consideration about the po ssibility of achieving high thermoelectric power. Calculational results sho w that in the case of Ge, the top of valence states is higher and the botto m of conduction states is rather lower compared to those in the case of Si. For Ge doped with Au, the atomic orbitals of Au contribute to energy level s just below the conduction states and above the valence states for Ge. A s imilar electronic structure is seen for Si doped with Au. In amorphous semi conductors, where Ge and Si are in contact with each other and doped with A u, ambiguous energy levels are usually formed near the bottom of the conduc tion states and the top of the valence states. Then, charge carriers may be introduced in the Si and Ge regions and may possibly enter the Ge and prec ipitated Au regions with a high energy. In addition, the energy levels of t he conduction and valence states are lifted and lowered, respectively, when the interatomic distance becomes shorter. Since the Seebeck coefficient fo r amorphous semiconductors is a function of electron energy and electric co nductivity which depend on the electron energy, the enhanced carrier energy will enhance thermoelectric power.