A method for sputtering simultaneously from electrically independent electrodes is described. The important design consideration is that the electrodes (cathodes) are enveloped by a single Crooke's dark space. Using this technique, alloy films (or in the case of reactive sputtering, mixed compound films) can be obtained. Since the electrodes are independent, the composition gradient (in depth) of the film can be varied at will by proper variation of applied voltages.