SURFACE-TOPOGRAPHY OF ERODED CU AND SI CATHODES IN A PIG ION-SOURCE

The surface topography development on a Cu sheet and a Si(111) wafer w as studied after being sputtered in a Penning ionization gauge (PIG) i on source using Ar gas. In the case of Cu, a high density of conical s tructure was developed on the surface. The most striking feature was t hat the individual cones, relatively large in size, were often coated with impurity layers. Some cones were decorated with concentric ring-l ike patterns on their surfaces. The overlying coating was thought to b e responsible for the initial growth of the cones and subsequent evolu tion of secondary protuberances on the surfaces of the cones. In the c ase of Si. though a few impurity-induced conical protrusions were form ed, the dominant morphology was in the form of etch pits. In addition to usual single cones, Si surface developed cones of dimeric structure and cluster of cones.