Photoluminescence enhancement induced by nanoparticles from La2O3 and CeO2 doped diamond-like carbon films

La2O3 and CeO2 doped composite hydrogen-free diamond-like carbon (DLC) films with thickness of 230-280 nm were deposited by unbalanced magnetron sputtering. Nanoparticles are formed on the surface of deposited films. Auger electron spectroscopy shows the C, O, La and Ce elements distribute uniformly along the depth direction, and they diffuse into the Si(1 0 0) substrate. X-ray photoelectron spectroscopy confirms the forming of La2O3 and CeO2 within the DLC films, and the amorphous DLC structure is not changed with the doping of rare earth oxides. G peak positions shift to higher wave numbers, and relative intensities ratio ID/IG increase of DLC films with the doping of La2O3 and CeO2, indicating the coherence between the ID/IG and G peak position. Furthermore, the photoluminescence (PL) obviously increase with the forming of nanoparticles and doping of La2O3 and CeO2. Specially, the PL intensity of 4% La2O3 and 4% CeO2 doped composite DLC films is 18.4 times of that of pure DLC films, which is beneficial for the increase of photoconversion efficiency of solar cells.