Epitaxial growth of MgO and Fe∕MgO∕Fe magnetic tunnel junctions on (100)-Si by molecular beam epitaxy

Abstract

Epitaxial growth of MgO barrier on Si is of technological importance due to the symmetry filtering effect of the MgO barrier in conjunction with bcc-ferromagnets. We study the epitaxial growth of MgO on (100)-Si by molecular beam epitaxy. MgO matches Si with 4:3 cell ratio, which renders Fe to be 45° rotated relative to Si, in sharp contrast to the direct epitaxial growth of Fe on Si. The compressive strains from Si lead to the formation of small angle grain boundaries in MgO below 5nm, and also affect the transport characteristics of Fe∕MgO∕Fe magnetic tunnel junctions formed on top.

Epitaxial growth of Heusler alloy Co2MnSi/MgO heterostructures on Ge(001) substrates

“…11 We observed streak patterns dependent on the electron injection direction, parallel to [100] Ge or [110] Ge , for each successive layer in the CMS/MgO/Ge(001) heterostructure during fabrication through in-situ RHEED observations. Furthermore, the spacing of the observed streak patterns of the MgO interlayer agreed well with that of the Ge (001) 17,18 and in contrast to the cube-oncube epitaxial growth of MgO on GaAs(001) 20,21 and MgO on Si(001) 22 with a 4:3 coincident site lattice.…”

Electrical spin injection in p-type Si using Fe/MgO contacts

“…For both samples, the MgO tunnel barrier (2 nm) and Fe electrode (10 nm) were deposited by electron-beam evaporation at 300°C and 100°C, respectively. The former is the optimum temperature for the growth of epitaxial MgO on Si(001) 22 . Finally, a 20-nm-thick Au capping layer was evaporated by using a conventional Knudsen-cell.…”

“…Whereas epitaxial growth of FM/MgO(001) for spin injection on Ge [11][12][13][14][15][16][17] and GaAs [18][19][20] has been intensively studied, the way towards epitaxial growth of MgO on Si is still not well established. Therefore, it is important to clarify the growth techniques and conditions for achieving epitaxial FM/MgO(001) layers on Si 4,7,[21][22][23] . In addition, the relationship between the crystal quality of the MgO barrier and the important spin-related physical parameters in Si, such as the spin lifetime and the magnitude of spin accumulation signal, should be investigated.…”

Growth of single-crystalline, atomically smooth MgO films on Ge(001) by molecular beam epitaxy

“…The insertion of a thin layer of insulator can also alleviate the strong Fermi-level pinning problem of metal/n-Ge contacts [17][18][19]. While the growth of MgO on Si(0 0 1) and GaAs(0 0 1) has been well studied [16,[20][21][22][23][24], very little work has been done on Ge(0 0 1). Therefore, the epitaxial growth of MgO thin films on Ge(0 0 1) is an important issue for the development of Ge-based spintronics.…”