MBE growth and properties of Fe3(Al,Si) on GaAs(100)

We report a successful epitaxial growth of an intermetallic compound Fe₃(Al,Si) on GaAs(100). Fe₃(Al,Si) has a BiF₃ (DO₃) structure with a lattice constant which can be adjusted to achieve a perfect lattice match with GaAs(100) face by tuning the relative concentration of Al to Si. The crystal growth was carried out in an MBE system consisting of dual growth chambers, one for III-V compound semiconductors and the other for growing metals ot group IV like Si. Sharp, elongated streaks were observed in the reflection high energy electron diffraction (RHEED) pattern after the deposition of one monolayer (ML) of Fe₃(Al,Si), indicating the attainment of an atomically smooth surface. The streaky RHEED pattern sharpened further until a 34 Å (12 MLs) thickness was reached, and retained similar quality in thicker films. The crystal structure of the films was also characterized by high-resolution X-ray diffraction and Rutherford backscattering/channeling analysis. A rocking curve as narrow as 0.03° full width half maximum along (400) Bragg reflection was obtained for an Fe_2.9(Al_0.4Si_0.7) film 1000 Å thick.