Mn behavior in Ge0.96Mn0.04 magnetic thin films grown on Si

Abstract

Mn behaviors in the Ge0.96Mn0.04 thin films grown on Si (001) substrates by molecular beam epitaxy were investigated by high resolution transmission electron microscopy, electron energy loss spectroscopy, and energy dispersive spectroscopy. Unlike the previously reported case of GeMn thin films grown on Ge, Mn has been found to be diffused toward to the surface during the thin film growth. When the Mn concentration is sufficiently high, Mn5Ge3 clusters may be formed. Further annealing of the high Mn concentrated thin film promotes the formation of α-Mn metallic clusters. We believe that all these extraordinary phenomena are attributed to Si as the substrate.

Mn-rich clusters in GeMn magnetic semiconductors: Structural evolution and magnetic property

“…Being compatible with current Si technology, Ge x Mn 1−x DMSs have attracted particular attention and extensive studies have been carried out to investigate their nanostructures and magnetic properties, both experimentally and theoretically [5][6][7][8][9][10][11][12][13][14]. It is well understood that inhomogeneous Mn doping in Ge thin films tends to generate Mn-rich magnetic intermetallic precipitates (such as Mn 5 Ge 3 [15][16][17][18][19][20] and Mn 11 Ge 8 [21][22][23]), or coherent Mn-rich clusters (such as tadpoles [24] and nanocolumns [13,25,26]), due to the low solubility of Mn in Ge.…”

Crystallographically oriented Zn nanocrystals formed in ZnO by Mn+-implantation

“…The thermal annealing makes Mn diffuse toward to the surface and the depth of ϳ160 nm. 7,8 Figure 1͑f͒ is a selected area electron diffraction ͑SAED͒ pattern, where two sets of diffraction patterns can be seen and both sets can be indexed as ZnO and Zn diffraction patterns. 11,12 Figures 2͑a͒ shows the -2 XRD scans for the samples with the implantation dose of 1 ϫ 10 17 cm −2 and unimplanted ZnO.…”

“…XTEM specimens were prepared using a tripod technique, followed by a final thinning using a Gatan precision ion polishing system. 7,8 The XTEM and energy filtered TEM ͑EFTEM͒ experiments were carried out in a FEI Tecnai F30 TEM with Gatan image filter system, operating at 300 kV. XRD was carried out in a two-dimensional diffraction system ͑Bruker-AXS, D8 Discover with GADDS͒ operating with Cu K␣ radiation ͑ = 1.5418 Å͒ at 40 kV and 40 mA.…”

Self-assembled Mn5Ge3 nanomagnets close to the surface and deep inside a Ge1−xMnx epilayer

“…Ge 1−x Mn x is most probably the so far best investigated system in this respect grown either on Ge substrates [2][3][4][5][6][7][8][9][10][11][12] or directly on Si wafers. 13 The magnetic properties of Ge 1−x Mn x layers with a small Mn content of few percent are substantially influenced by inhomogeneities of the distribution of Mn atoms in the Ge host lattice. Depending on the substrate temperature during molecular beam epitaxial ͑MBE͒ growth, coherent cubic Mn-rich clusters 7,14 or ferromagnetic hexagonal Mn 5 Ge 3 precipitates can occur.…”

“…The in-plane orientation is derived to ͑110͒ Mn 5 Ge 3 ʈ ͑110͒ Ge but its c hex -axis is inclined to ͓001͔ Ge . Mechanisms to explain the formation of distinct buried and surface precipitate classes could be Mn diffusion toward the surface 13 and the need for a critical layer thickness 18 for incoherent precipitate nucleation.…”