there is a small problem with different sputter rate for heavy and light atoms (but much smaller than in the case of evaporation)
during the sputtering the concetration will change
when the concentrations in the target reach the ratio written below, then the ratio will remain constant, and thus also the film will be stoichiometric (SA, SB are the sputtering rates of the two components A and B, CA and CB are the initial concentrations in the source)
multiple targets
The power consumed on each target can be adjusted, to obtain the desired sputtering rates and final composition
Substrate preparation
