Development of the surface topography on polycrystalline metals by ion bombardment investigated by scanning electron microscopy

Abstract

Polycrystalline Cu and Ag surfaces were bombarded by a monoenergetic parallel beam of 10 keV Ar+ ions from various directions of incidence. The relief formation at grain boundaries has been studied by means of a scanning electron microscope. In a large range of angles of incidence only single slopes are observed at the great majority of grain boundaries. The formation of slopes has been studied quantitatively with stereo pairs. The change of the direction of incidence causes the formation of new areas starting from the grain boundaries. With grazing incidence only a small part of grain boundaries will be visible. Including the special cases the formation of the areas observed can be described with a simple model based on the influence of geometrical parameters, especially the beam direction (channelling effect), on the sputtering rate.

Unusual pattern formation on Si(100) due to low energy ion bombardment

“…Thus, unusual pattern formation in our case may be related to sputtering. Relief structures are observed under sputtering due to low-energy ion bombardment of single crystalline and amorphous solids [20,21]. In the latter report, the starting point of relief structures was attributed to a mechanism proposed by Sigmund [13].…”

First-wall erosion in fusion reactors

“…A process not being discussed here in detail is surface faceting, which means the development of grooves and hills on a solid surface due to thermal treatment and/or preferential sputtering [13][14][15][16][17][18]. Sputtering yields are different for different crystal surfaces and orientations, which is one of the reasons for non-uniform erosion of polycrystalline material.…”

“…The initiation and spread of this cascade are influenced by the structure and orientation of the lattice, by channeling [7,10], and focusing [7,10]; however, polycrystalline material can be regarded with good accuracy as having randomly distributed lattice atoms as long as the individual grains are randomly oriented [11]. Single-crystal effects come into play with polycrystalline materials only because of surface faceting [6,[13][14][15][16][17][18].…”

Faceting mechanism in the sputtering process

“…In sputtering experiments with 10 keV Ar ions we investigated the time dependence of development of the relief structure on Ag single crystals. The ion beam apparatus i s described in (3). Fig.…”