Spectromicroscopy for Addressing the Surface and Electron Transport Properties of Individual 1-D Nanostructures and Their Networks

Southern Illinois University at Carbondale, Carbondale, Illinois 62901-4401, USA.
ACS Nano (Impact Factor: 12.88). 11/2008; 2(10):1993-2000. DOI: 10.1021/nn8003313
Source: PubMed


Understanding size/dimensionality-dependent phenomena and processes relevant to chemical sensing and catalysis requires analytical methods with high surface sensitivity, which can exploit the structure and composition of nanomaterials at their natural length scales and working conditions. In the present study, we explored the potentials and complementary capabilities of several surface-sensitive microscopy approaches to shed light on the properties of individual SnO(2) nanowires and their networks. Our results demonstrate the unique opportunities provided by synchrotron-based photoelectron microscopies for surface-sensitive structural and chemical analysis, including in situ characterization of electron transport properties of a nanostructure wired as an active element in chemiresistor devices.

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    ABSTRACT: Contactless monitoring with photoelectron microspectroscopy of the surface potential along individual nano-structures, created by the X-ray nanoprobe, opens exciting possibilities to examine quantitatively size-and surface-chemistry-effects on the electrical transport of semiconductor nanowires (NWs). Implementing this novel approach—which combines surface chemical microanalysis with conductivity measurements—we explored the dependence of the electrical properties of undoped GaAs NWs on the NW width, temperature and surface chemistry. By following the evolution of the Ga 3d and As 3d core level spectra, we measured the position-dependent surface potential along the GaAs NWs as a function of NW diameter, decreasing from 120 to ~20 nm, and correlated the observed decrease of the conductivity with the monotonic reduction in the NW diameter from 120 to ~20 nm. Exposure of the GaAs NWs to oxygen ambient leads to a decrease in their conductivity by up to a factor of 10, attributed to the significant decrease in the carrier density associated with the formation of an oxide shell.
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