Structural and optical properties of fullerene-like amorphous carbon with embedded dual-metal nanoparticles

Dual-metal nanoparticles were simultaneously embedded into amorphous carbon (a-C) matrix at room temperature. As-deposited Au/a-C/Fe sandwich composite multilayer films were fabricated by alternating multitarget pulsed laser deposition. More sp2 carbon content, narrower Tauc optical gap and stronger photoluminescence intensity of the amorphous carbon films were observed after metal-embedding. Especially for Au/a-C/Fe sandwich films, the fullerene-like microstructure demonstrated that the dual-metal embedding modulated greatly the intrinsic structure and properties of the a-C films. These results were attributed primarily to the extended state around the metal deep level in the band gap and the narrowing of the π and π∗ band edge states. The metal deep level defects contributed chiefly to non-radiative recombination.