Formation of Self-Assembled Monolayer on Cleaved Compound Semiconductor Surfaces and Its Nano-structure on A1GaAs/GaAs Heterostructure

Hirotaka OHNO; Larry Akio NAGAHARA; Shangjr GWO; Wataru MIZUTANI; Hiroshi TOKUMOTO

doi:10.1380/jsssj.18.373

Hirotaka OHNO, Larry Akio NAGAHARA, Shangjr GWO, Wataru MIZUTANI, Hiroshi TOKUMOTO

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JOURNAL FREE ACCESS

1997 Volume 18 Issue 6 Pages 373-379

DOI https://doi.org/10.1380/jsssj.18.373

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Published: June 10, 1997 Received: October 16, 1996 Available on J-STAGE: August 07, 2009 Accepted: October 16, 1996 Advance online publication: - Revised: -
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Date of correction: August 07, 2009 Reason for correction: - Correction: ABSTRACT Details: Wrong : Self-assembled monolayer(SAM)s of 1-octadecanethiol [ODT: CH₃(CH₂)₁₇SH] were formed on bare GaAs substrates by cleaving the substrates in a 1 mM ethanol. Both growth process and surface properties were investigated using surface force microscopy (SFM) and x-ray photoelectron spectroscopy (XPS). Dendritic shape of islands &sim;20 nm in diameter appeared for 30 sec immersion. As the immersion time increased, these islands coalesced, connected each other, and finally the surfaces were uniformly covered with the monolayer after 1 day of immersion. High-resolution friction force microscope (FFM) images revealed a periodic structure that had two type of lines on the SAM. A structural model of the SAM, which successfully explained these experimental results, was presented. XPS results also indicated that SAM of ODT can protect a GaAs surface from oxidation. Furthermore, we demonstrated the formation of nanostructural SAM of ODT by use of A1GaAs/GaAs hetero-epitaxial substrates. SFM images revealed that ODT molecules selectively chemisorbed on GaAs surface regions resulting in the formation of nano-wires, 10 nm in width and &sim;1 nm in height. The mechanism of the nanostructural SAM formation was also discussed.
Right : Self-assembled monolayer(SAM)s of 1-octadecanethiol [ODT: CH₃(CH₂)₁₇SH] were formed on bare GaAs substrates by cleaving the substrates in a 1 mM ethanol. Both growth process and surface properties were investigated using surface force microscopy (SFM) and x-ray photoelectron spectroscopy (XPS). Dendritic shape of islands ∼20 nm in diameter appeared for 30 sec immersion. As the immersion time increased, these islands coalesced, connected each other, and finally the surfaces were uniformly covered with the monolayer after 1 day of immersion. High-resolution friction force microscope (FFM) images revealed a periodic structure that had two type of lines on the SAM. A structural model of the SAM, which successfully explained these experimental results, was presented. XPS results also indicated that SAM of ODT can protect a GaAs surface from oxidation. Furthermore, we demonstrated the formation of nanostructural SAM of ODT by use of A1GaAs/GaAs hetero-epitaxial substrates. SFM images revealed that ODT molecules selectively chemisorbed on GaAs surface regions resulting in the formation of nano-wires, 10 nm in width and ∼1 nm in height. The mechanism of the nanostructural SAM formation was also discussed.

Abstract

Self-assembled monolayer(SAM)s of 1-octadecanethiol [ODT: CH₃(CH₂)₁₇SH] were formed on bare GaAs substrates by cleaving the substrates in a 1 mM ethanol. Both growth process and surface properties were investigated using surface force microscopy (SFM) and x-ray photoelectron spectroscopy (XPS). Dendritic shape of islands ∼20 nm in diameter appeared for 30 sec immersion. As the immersion time increased, these islands coalesced, connected each other, and finally the surfaces were uniformly covered with the monolayer after 1 day of immersion. High-resolution friction force microscope (FFM) images revealed a periodic structure that had two type of lines on the SAM. A structural model of the SAM, which successfully explained these experimental results, was presented. XPS results also indicated that SAM of ODT can protect a GaAs surface from oxidation. Furthermore, we demonstrated the formation of nanostructural SAM of ODT by use of A1GaAs/GaAs hetero-epitaxial substrates. SFM images revealed that ODT molecules selectively chemisorbed on GaAs surface regions resulting in the formation of nano-wires, 10 nm in width and ∼1 nm in height. The mechanism of the nanostructural SAM formation was also discussed.

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