Abstract: A portable data carrier, suitable for operation in either a contacted or a contactless mode, includes a clock signal input pad and a clock detection circuit. The clock input pad includes an output that is coupled to a selection circuit having a first input and a second input. An input for the selection circuit is coupled to the output of the clock detection circuit. The microprocessing unit follows the clock being transmitted via the clock input pad in the contacted mode of operation if the clock detection circuit confirms presence of such a clock signal. Otherwise, the contactless mode of operation is chosen, where the microprocessing unit follows a radio frequency clock.

Abstract: A metal-semiconductor layer (26) is formed over an insulating layer (20) such that the metal-semiconductor layer (26) is graded to have varying amounts of the semiconductor and metal throughout the layer. In one embodiment, the metal-semiconductor layer (26) has relatively higher silicon content near the layer's lower and upper surfaces. At the midpoint, the layer is close to stoichiometric tungsten silicide. In another embodiment, a metal-semiconductor-nitrogen layer is formed having nitrogen nearer the lower surface and essentially no nitrogen near the upper surface. The layer (26) can be formed using chemical vapor deposition or sputtering.