Structural and magnetic properties of Ge{sub 1-x}Mn{sub x} thin films grown on Ge (001) substrates

Journal Article · Sat Oct 01 04:00:00 EDT 2011 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.3638701· OSTI ID:22038732

Yada, Shinsuke; Nam Hai, Pham; Tanaka, Masaaki ^[1]; Sugahara, Satoshi ^[2]

---

1. Department of Electrical Engineering and Information Systems, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)
2. Imaging Science and Engineering Laboratory, Tokyo Institute of Technology, 4259-G2-14 Nagatsuta, Yokohama, Kanagawa 226-8502 (Japan)

We investigate the structural and magneto-optical properties of Mn-doped Ge (Ge{sub 1-x}Mn{sub x}) films with self-organized nanocolumns, grown on Ge (001) substrates by molecular beam epitaxy (MBE), in which the substrate temperature (T{sub S}) and growth rate (R{sub G}) are varied. Transmission electron microscopy (TEM) observations and magnetic circular dichroism (MCD) measurements reveal that Mn-rich nanocolumnar precipitation is formed in the Ge{sub 1-x}Mn{sub x} films grown at T{sub S} {<=} 100 deg. C, with keeping the size and spacing. At higher T{sub S} ({>=}150 deg. C), ferromagnetic Mn{sub 5}Ge{sub 3} clusters are formed. It is also found that the Mn distribution in the Ge{sub 1-x}Mn{sub x} films can be controlled: By lowering T{sub S} or increasing R{sub G}, the Mn content x{sub nc} in the nanocolumns decreases and Mn atoms are more distributed into the Ge matrix, and eventually the magnetic properties are changed. The formation of the nanocolumns is explained by the spinodal decomposition in the layer-by-layer growth mode. We analyzed the periodicity and Mn content x{sub nc} of nanocolumns by using the Cahn-Hilliard equation.

• OSTI ID: 22038732
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 7 Vol. 110; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CRYSTAL GROWTH
DOPED MATERIALS
FERROMAGNETIC MATERIALS
GERMANIUM
GERMANIUM COMPOUNDS
LAYERS
MAGNETIC CIRCULAR DICHROISM
MAGNETIC PROPERTIES
MANGANESE COMPOUNDS
MOLECULAR BEAM EPITAXY
NANOSTRUCTURES
OPTICAL PROPERTIES
SEMICONDUCTOR MATERIALS
SUBSTRATES
TEMPERATURE DEPENDENCE
THIN FILMS
TRANSMISSION ELECTRON MICROSCOPY