Electronic and Thermal Characterization of Lithiated Silicon Nanowires
Dominik Bauer a, Teute Bunjaku a, Mathieu Luisier a
a Swiss Federal Institute of Technology (ETH) Zurich, Switzerland
Proceedings of nanoGe Fall Meeting19 (NGFM19)
#CharDy19. Charge Carrier Dynamics
Berlin, Germany, 2019 November 3rd - 8th
Organizers: Marcus Scheele and Maksym Yarema
Poster, Dominik Bauer, 373
Publication date: 18th July 2019

An ab-initio density-functional approach is used to study the lithiation of crystalline silicon nanowires. Quantum transport calculations are performed to characterize changes in the electrical current flowing at varying lithium concentrations. It is found that the insertion of lithium into crystalline silicon leads to a step-like process, where each Si shell is successively lithiated from the outside. The volume of the nanowire quadruples for the maximum lithium concentration and the silicon network becomes fully amorphous. Simultaneously, a current trajectory analysis within the lithiated nanowires reveals that the main contribution shifts from the center to the surface of the nanostructure as the Li concentration increases.

Additionally, the effect of surface roughness on electronic as well as thermal properties is investigated. Therefore, the lithiated nanowire is extended along its transport direction and the surface atoms are randomly displaced. Due to the size of the system, a combination of the GPW and GAPW method and an empirical approach is used [1,2]. The Hamiltonian of the nanowire is extracted with the former and the dynamical matrix with the latter. Due to this mix of methods, it is possible to calculate the respective parts for different lengths of each system and calculate the electronic and thermal conductivities with the so-called "dR/dL" method [3]. Results for both studies will be shown and discussed.

This research was supported by the European Research Council under Grant Agreement No 335684-E-MOBILE, and by CSCS under Project Nos. s876 and pr28.

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