Island growth on solid surfaces unde ion irradiation

The growth of thin solid films on solid surfaces is an industrially wide-spread method to adapt the characteristics of materials to the appropriate needs. The exact control of the evaporating processes is substantial in particular to avoid the formation of islands with epitactic growth. Frequently the irradiation of low-energy ions (with energies below approximately 1 keV) is used for this purpose. A significant change of the island growth on solids can be observed by ion irradiation within the keV energy range. Altogether it can be stated that Helium irradiation increases the islands lateral dimensions when compared to unirradiated samples while at higher temperatures only a slight broadening and flattening of the islands is observed. With Argon irradiation the island diameter stays approximately constant with increasing thickness of the adsorbate. At high temperatures of 550-1260 C of the Knudsen evaporation cell, i.e. high evaporation rates, it can be observed that by using Argon irradiation Bismuth layers originate in contrast to the islands in the not irradiated sample areas. The molecular dynamics simulation showed as an important new effect of irradiation that the islands can melt and evaporate, and may later on condense to the surface. The resulting islands are much broader and flatter than those without irradiation. The newly formed islands show twinning, facetting and clearly visible reordering