Electronic Structure Calculations for Au-doped Ge and Si with a Possible High Thermoelectric Power

概要

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Molecular orbital calculations were performed to investigate electronic structures of gold-doped germanium and silicon with consideration about the possibility of achieving high thermoelectric power. Calculational results show that in the case of Ge, the top of valence states is higher and the bottom 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 levels just below the conduction states and above the valence states for Ge. A similar electronic structure is seen for Si doped with Au. In amorphous semiconductors, where Ge and Si are in contact with each other and doped with Au, ambiguous energy levels are usually formed near the bottom of the conduction 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 precipitated Au regions with a high energy. In addition, the energy levels of the conduction and valence states are lifted and lowered, respectively, when the interatomic distance becomes shorter. Since the Seebeck coefficient for amorphous semiconductors is a function of electron energy and electric conductivity which depend on the electron energy, the enhanced carrier energy will enhance thermoelectric power.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2001-05-15