Formation of Island Structures during Melting Process of Tin Films on Amorphous Carbon Substrate

Abstract

The results of research devoted to formation of ordered arrays of particles during melting process of tin films on amorphous carbon substrate are given in the present work. Using scanning electron microscopy the histograms of particle size distribution are constructed for films of different mass thickness. The size dependences of the most probable radius of particles, which are formed during the melting process, and the half-width values of the corresponding histograms are obtained as well. The excess energy, which provides a decomposition of the initially continuous film into separate islands, is estimated and its size dependence is built. As shown, the melting process of films, which are condensed in island structures, provides larger filling coefficients in comparison with the melting process of initially continuous films.

Phase Diagram of In–Pb Alloy in Condensed Films

“…The value is put down the vertical axis and shows (up to the factor considering the wetting angle) the volume of the substance, which falls for the particles; the radius r of which fell into the selected step of the building of the histogram Δ r ( A is the area of the image from which the histogram was calculated). [ 26 ]…”

“…AΔr is put down the vertical axis and shows (up to the factor considering the wetting angle) the volume of the substance, which falls for the particles; the radius r of which fell into the selected step of the building of the histogram Δr (A is the area of the image from which the histogram was calculated). [26] It is seen that in the significant concentrations interval, the most probable size of the particles formed during the alloy melting is almost constant.…”

“…After samples condensation and finalization of the thermal influence, the thickness of the films was additionally refined according to the data of scanning electron microscopy (SEM) studies. It is convenient to use the approach tested by Dukarov et al [ 26 ] for this. Above the liquidus line, i.e., in the area of the completely molten film, a series of SEM images was obtained corresponding to a change in the concentration of one of the components in the range of 0–100%.…”

“…Diffusion in the liquid phase may be faster, but as a result of the melting (and in the thin layers, it occurs earlier), the film breaks into separate isolated droplets; the sizes of which are several times bigger than the film thickness. [22][23][24][25] It is clear, that in a film consisting of liquid-isolated particles, there will be no violation of the initial distribution of the substance along the concentration gradient.…”

“…In this regard, the presence of a minimum looks natural and indicates the preservation of the continuous state of the initial film immediately before the melting moment. [26] With a further increase in the indium content, the most probable size of the appearing particles decreases, and the substrate coverage with the film increases to 0.25. This value of the coverage is typical for the films in which a continuous structure was not formed under the condensation process, i.e., they remained island-type all the time.…”