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Charge localization in [112] Si/Ge and Ge/Si core-shell nanowires

TitleCharge localization in [112] Si/Ge and Ge/Si core-shell nanowires
Publication TypeJournal Article
Year of Publication2010
AuthorsLiu N, Li YR, Lu N, Yao YX, Fang XW, Wang CZ, Ho KM
Journal TitleJournal of Physics D-Applied Physics
Volume43
Pages275404
Date Published07/14
ISBN Number0022-3727
Accession NumberISI:000279003700019
Keywordselectrical detection, FIELD-EFFECT TRANSISTORS, heterostructures, metals, molecular-dynamics, NANOSENSORS, SENSOR, silicon nanowires
Abstract

We report a first-principles study of Ge/Si and Si/Ge core/shell nanowires (NWs) along the [1 1 2] direction with a diameter of similar to 20 angstrom using density-functional theory. Our results show that for both NW structures the band gaps are indirect and are significantly larger than the gaps of the bulk crystalline Si and Ge. The quantum well confinement effect in these NWs is found to be modified by a type II lineup of band structures. Moreover, the carriers on the conduction band minimum are strongly localized in the Si region while the carriers on the valence band maximum are located mainly in the Ge region. The charge separation and localization characters make the NWs good candidates for nanochannels in field effect devices, solar cells with higher efficiency and high mobility heterostructures due to the spatial separation of one-dimensional electron gas and one-dimensional hole gas.
URL<Go to ISI>://000279003700019
DOI10.1088/0022-3727/43/27/275404