To the theory of dynamic surface changes while high-temperature field evaporation

Abstract

Let us determine high temperature field evaporation as a process accompanied by intensive surface diffusion, growth of microprotrusions and the other even more complicated formations such as: outgrowths, steps etc. Thermal-field (TF) microprotrusions growing in the area of highest electric field have two different functions: they work as a substrate material outflows while field evaporation takes place and, at the same time, make for the layer by layer crystal growth providing a nucleation of new atomic layers as well. The competition of crystal growth and dissolution processes leads to the cyclic (pulsing) evaporation mechanism in the regions of close-packed planes of the tip's single crystal at very specific conditions. This particular mechanism is characterized by the collapse of rings formed by chains of TF microprotrusions during field desorption imaging. The formation of the ring had been associated with the growth of macro-outgrowth (crystal growth in direction normal to plane) while rapid collapse interpreted as avalanche-like evaporation of such outgrowth followed by decrease of its diameter. The present paper gives quantitative analysis of this phenomenon, defines more precisely some process peculiarities and considers some features of the evaporation mechanism like the pause in the proceedings of the collapse of the rings, for example.