Integration of Single -Walled Carbon Nanotubes With Gallium Arsenide(110) and Indium Arsenide(110) Surfaces: A Scanning Tunneling Microscopy Study

Abstract

150 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2007.In an effort to better elucidate the influence of semiconducting surfaces on supported carbon nanotubes, we have used scanning tunneling microscopy (STM) and spectroscopy (STS) to investigate the physical and electronic behavior of single-walled carbon nanotubes (SWNTs) coupled to GaAs(110) and InAs(110) substrates in ultrahigh vacuum (UHV). Both flat and stepped III-V(110) surfaces were obtained through in situ cleavage and nanotubes subsequently deposited onto the substrates via an UHV-compatible dry contact transfer procedure. STM images indicate that SWNTs on these III-V(110) surfaces possess a striking orientation-dependent adhesion preference, with nanotubes exhibiting an enhanced stability when aligned along the substrate lattice rows. STS measurements reveal the substrate-induced charge transfer doping of III-V-supported SWNTs and suggest the presence of potential orientation-dependent electronic effects in nanotubes on InAs substrates. The effects of proximal surface features, such as steps, on supported SWNTs are also explored. In addition, the simultaneous topographic and electronic imaging capabilities of the STM are exploited to obtain a detailed characterization of a naturally occurring metal-semiconductor intramolecular nanotube junction. Our studies indicate that local surface properties can have a considerable effect on the physical and electronic character of supported SWNTs, suggesting the exciting possibility of substrate-engineering for the design and fabrication of novel nanotube-based electronic devices.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD