Epitaxial Growth, Structure, and Composition of Fe Films on GaAs(001)-2x4
NAVAL RESEARCH LAB WASHINGTON DC
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The structure and composition of Fe films grown on As-terminated GaAs001-234 surfaces at 175 C has been studied in situ with scanning tunneling microscopy STM, photoelectron diffraction PED, and x-ray photoelectron spectroscopy XPS. The GaAs surfaces were prepared by molecular beam epitaxy MBE and exhibited large atomically well-ordered terraces. We find that the 234 reconstruction has a significant impact on the Fe nucleation and growth, with initial nucleation occurring at As-dimer sites. STM reveals that the first half-monolayer of Fe forms small two-dimensional islands along the As-dimer rows before growing onto the adjacent Ga-rich rows, with no evidence of substrate disruption. PED indicates that the growth is predominantly layer by layer, with the growth front for the nth deposited layer limited to the n 1th layer. XPS spectra show that the Fe films include a concentration gradient of Ga and As out-diffused from the interface, with some of the As segregating to the Fe surface, similar to previous results obtained for growth on non-MBE prepared GaAs surfaces. Possible mechanisms for the film growth and the origins of the intermixing are discussed.
- Inorganic Chemistry
- Electrical and Electronic Equipment