Abstract: The present invention is directed toward an improved heater chip for an ink jet printer. The heater chip has a diamond-like-carbon coating that functions as the cavitation and passivation layers of the heating elements on the heater chip. To improve the efficiency of the heater chip, the diamond-like-carbon coating is surrounded by a material that has a lower thermal conductivity than diamond. This surrounding layer limits thermal diffusion from the heating elements into the heater chip. A smoothing layer of tantalum is deposited over the diamond-like-carbon layer to insure that vaporization of the ink occurs at the ink's superheat limit. The diamond-like-carbon layer is preferably less than 8700 Angstroms in thickness such that less than 1 microjoule of energy is required to expel of ink droplet having a mass between 2-4 nanograms.