Electric Current Driven Formation of Micro-and Nano-sized Beads in Thin Cr Films

Nano films of chromium with thicknesses from 20 to 200 nm were deposited on silicon substrates and were treated by electric current induced by AFM tip in ambient atmosphere. The melting on the nanoscale, electric current induced migration of the material and chemical reaction of oxidization of chromium were revealed in melting craters around the point of application of the current by optical and electronic scanning microscopy, AFM, and Raman spectroscopy. The flow of the material induced by electric current is accompanied by formation and motion of the matrix of the spherical nanoparticles (beads) in the crater of melt on its periphery. The reaction of chromium oxidation and surface tension of the melted material on the silicon substrate are expected to be responsible for the matrix of nano beads formation under comparatively small currents. Raman spectroscopy confirms that in the vicinity of the periphery of the melted craters around AFM tip application, the beads of oxide phase Cr
₂
O
₅
are present.