Ion Dose Effect in Thin Film Formation on Nb(100)

The growth of metal films under the influence of ion bombardment has attracted considerable interest recently in connection with ion beam deposition. In ion beam deposition condensation and surface damage are not separable. Such a separation is, however, possible if the metal is thermally evaporated in small doses and bombarded in between doses with ions whose nature, energy and angle of incidence can be chosen freely. The secondary ions produced by these ions can simultaneously be used to characterize the film. We have studied the initial growth of Cu and Pd on Nb(100) in this manner. These two systems differ fundamentally in that Pb alloys with Nb while Cu does not. A comparison of the two systems should, therefore, give some insight into the influence of alloyibility on the ion beam influence.