Nanoscale mapping of the W/Si(001) Schottky barrier
Durcan, Chris A.
LaBella, Vincent P.
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Subjectballistic electron emission microscopy; W/Si(001) Schottky barrier; ballistic hole emission microscopy; microscopy; transmission electron microscopy; Rutherford backscattering spectrometry; interfacial tungsten silicide; Prietsch Ludeke fitting exponent; histogram; power law BEEM model; Gaussian component; interface dipole model
The W/Si(001) Schottky barrier was spatially mapped with nanoscale resolution using ballistic electron emission microscopy (BEEM) and ballistic hole emission microscopy (BHEM) using n-type and p-type silicon substrates. The formation of an interfacial tungsten silicide is observed utilizing transmission electron microscopy and Rutherford backscattering spectrometry. The BEEM and BHEM spectra are fit utilizing a linearization method based on the power law BEEM model using the Prietsch Ludeke fitting exponent. The aggregate of the Schottky barrier heights from n-type (0.71 eV) and p-type (0.47 eV) silicon agrees with the silicon band gap at 80 K. Spatially resolved maps of the Schottky barrier are generated from grids of 7225 spectra taken over a 1 um x 1 um area and provide insight into its homogeneity. Histograms of the barrier heights have a Gaussian component consistent with an interface dipole model and show deviations that are localized in the spatial maps and are attributed to compositional fluctuations, nanoscale defects, and foreign materials.