We have deposited diamondlike carbon, carbon nitride, and titanium nitride biocompatible coatings using pulsed laser deposition and magnetron sputtering on metallic (cobalt-chromium and titanium- 6% aluminum- 4% vanadium) and polymeric (high-density polyethylene) substrates commonly used in human prosthetic devices. A major advantage of the magnetron sputtering deposition technique is that it provides conformal coverage of large-area films. The coatings were characterized by electron diffraction and imaging, Raman spectroscopy, X- ray photoelectron spectroscopy, and electron- energy loss spectroscopy, and nanoindenter hardness measurements. The physical properties (especially hardness) of the diamondlike carbon films were controlled using carbide and noncarbide forming elements. By varying the doping concentration as a function of thickness, functionally gradient materials with superior tribological and mechanical properties can be created. The implications of these results are discussed in the context of biomedical applications.