Scanning tunneling microscopy studies of niobium carbide (100) and (110) surfaces

R.M. Tsong*, M. Schmid, C. Nagl, P. Varga, R.F. Davis+ and I.S.T. Tsong#

Institut für Allgemeine Physik, Technische Universität Wien, A-1040 Wien, Austria
*Permanent address: College of William and Mary, Williamsburg, VA 23186, USA
+Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695, USA
#Department of Physics and Astronomy, Arizona State University, Tempe, AZ 85287-1504, USA

Surf. Sci 366 (1996) 85-92

Scanning tunneling microscopy (STM) studies were conducted on the surfaces of NbC0.75(100) and NbC0.865(110) single crystals after in-situ cleaning treatments of sputtering and annealing cycles. STM images show atom-resolved structures on both surfaces. On NbC0.75(100), localized areas of a square (1x1) structure were observed, together with regions of hexagonal structure, indicative of a coexisting surface phase, possibly that of Nb4C3-x. On the NbC0.865(110) surface, a ridge-and-valley grating structure consisting of both (4x1) and (5x1) geometries was observed over large areas. The nanometer-scale faceting phenomenon may be common to the (110) surfaces of most transition-metal carbides.

Corresponding author: M. Schmid (schmid< encoded email address >).

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