Sharp Fe/MgO/Ge(001) epitaxial heterostructures for tunneling junctions

Journal Article · Sat Jan 01 04:00:00 EST 2011 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.3554834· OSTI ID:1018584

Petti, D. ^[1]; Cantoni, M. ^[1]; Rinaldi, C. ^[1]; Brivio, S. ^[1]; Bertacco, R. ^[1]; Gazquez Alabart, Jaume ^[2]; Varela del Arco, Maria ^[2]

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1. Politecnico di Milano
2. ORNL

We report on the growth of epitaxial Fe/MgO/Ge(001) heterostructures by molecular beam epitaxy. The lowest oxidation and highest sharpness of the MgO/Ge interface, corresponding to a transition layer on the order of one Ge unit cell, is obtained for room temperature growth of the MgO layer followed by annealing in a vacuum at 500 C. In these conditions, the MgO layer grows epitaxially on Ge(001) with the [110] direction parallel to the [100] direction of Ge, at variance with the cube-on-cube growth on Si(001) and GaAs(001). However, in some cases, the cube-on-cube growth mode of MgO on Ge competes with the mode involving a 45{sup o} rotation, as revealed by transmission electron microscopy and photoelectron diffraction data on MgO films grown at 300 C without postannealing, and on p-doped Ge substrates. For the Fe overlayer, in all the cases reported, room temperature growth followed by annealing up to 200 C gives rise to a sharp interface and the well-known 45{sup o} rotation of the Fe lattice with respect to the MgO lattice.

• Research Organization: Oak Ridge National Laboratory (ORNL)
• Sponsoring Organization: SC USDOE - Office of Science (SC)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1018584
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 8 Vol. 109; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ANNEALING
DIFFRACTION
MOLECULAR BEAM EPITAXY
OXIDATION
ROTATION
SUBSTRATES
TRANSMISSION ELECTRON MICROSCOPY
TUNNELING