Band alignments in Fe/graphene/Si(001) junctions studied by x-ray photoemission spectroscopy

Jean-Christophe Le Breton 1 Sylvain Tricot 1 Gabriel Delhaye 1 B. Lépine 1 Pascal Turban 1 Philippe Schieffer 1
1 IPR - Institut de Physique de Rennes
Abstract : The control of tunnel contact resistance is of primary importance for semiconductor-based spintronic devices. This control is hardly achieved with conventional oxide-based tunnel barriers due to deposition-induced interface states. Manipulation of single 2D atomic crystals (such as graphene sheets) weakly interacting with their substrate might represent an alternative and efficient way to design new heterostructures for a variety of different purposes including spin injection into semiconductors. In the present paper, we study by x-ray photoemission spectroscopy the band alignments and interface chemistry of iron-graphene-hydrogenated passivated silicon (001) surfaces for a low and a high n-doping concentration. We find that the hydrogen passivation of the Si(001) surface remains efficient even with a graphene sheet on the Si(001) surface. For both doping concentrations, the semiconductor is close to flat-band conditions which indicates that the Fermi level is unpinned on the semiconductor side of the Graphene/Si(001):H interface. When iron is deposited on the graphene/Si(001):H structures, the Schottky barrier height remains mainly unaffected by the metallic overlayer with a very low barrier height for electrons, a sought-after property in semiconductor based spintronic devices. Finally, we demonstrate that the graphene layer intercalated between the metal and semiconductor also serves as a protection against iron-silicide formation even at elevated temperatures preventing from the formation of a Si-based magnetic dead layer. © 2016 Author(s).
Keywords : Elevated temperature Hydrogen passivation Heterojunctions Interface states Iron Magnetoelectronics Passivation Photoelectron spectroscopy Schottky barrier diodes Semiconducting silicon Semiconductor devices Semiconductor doping Silicides Silicon Substrates Doping concentration Interface chemistry Magnetic dead layers Schottky barrier heights Spintronic device X ray photoemission spectroscopy Graphene
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Submitted on : Tuesday, September 27, 2016 - 4:30:52 PM
Last modification on : Friday, November 29, 2019 - 3:26:05 PM

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Jean-Christophe Le Breton, Sylvain Tricot, Gabriel Delhaye, B. Lépine, Pascal Turban, et al.. Band alignments in Fe/graphene/Si(001) junctions studied by x-ray photoemission spectroscopy. Applied Physics Letters, American Institute of Physics, 2016, 109, pp.051601. ⟨10.1063/1.4960199⟩. ⟨hal-01372806⟩

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