AVS 50th International Symposium
    Magnetic Interfaces and Nanostructures Wednesday Sessions
       Session MI+TF-WeA

Paper MI+TF-WeA2
Epitaxial Growth of Ferromagnetic Fe Overlayers on CH@sub 3@CSNH@sub 2@ - Passivated GaAs(100)-S(2x1) Reconstruction

Wednesday, November 5, 2003, 2:20 pm, Room 316

Session: Magnetic Thin Films
Presenter: E.D. Lu, University of Wisconsin, Milwaukee
Authors: E.D. Lu, University of Wisconsin, Milwaukee
H.T. Johnson-Steigelman, University of Wisconsin, Milwaukee
P.F. Lyman, University of Wisconsin, Milwaukee
Correspondent: Click to Email
Epitaxial growth of ferromagnetic metallic Fe overlayers on thioacetamide (CH@sub 3@CSNH@sub 2@)-passivated GaAs(100)-S(2x1) reconstructed surfaces at room temperature (RT) has been investigated by low energy electron diffraction (LEED), x-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). Prior to Fe deposition, GaAs(100) wafers were passivated by CH@sub 3@CSNH@sub 2@ solution then annealed between 320°C and 450°C under UHV. A clear (2x1) reconstructed LEED pattern with around 1 monolayer (ML) sulfur coverage resulted. Upon deposition of Fe at RT, epitaxial bcc(100) Fe overlayers could be grown from 3 to 40 ML. XPS and AES have revealed that only an initial interface reaction (<4ML) takes place between the evaporated Fe overlayer and GaS sulfide passivation layers. Upon annealing, the Fe/S-GaAs(100) heterostructure appears stable up to 320°C; solid state reaction and/or interdiffusion of the layers starts at higher annealing temperatures, becoming severe by 450°C. Nonetheless, a LEED pattern is observed even after intermixing. These results indicate that the S passivation layer may inhibit Ga and As outdiffusion at modest substrate temperatures, and may thus suppress or reduce the formation of an anti-ferromagnetic Fe@sub 2@As dead layer or other unfavorable Fe@sub 3@Ga@Sub 2-x@As@sub x@ phases.