Carbon nitride thin films prepared by nitrogen ion assisted pulsed laser deposition of graphite using KrF excimer laser

Carbon nitride films were prepared by nitrogen ion assisted pulsed KrF exci mer laser deposition of graphite onto Si(100) substrates. The energy of nit rogen ions was changed between 25 and 1500 eV. The transport ratio of carbo n atoms to nitrogen ions at the substrate was 1.0. The dependence of the st oichiometry and formed chemical bonds on the nitrogen ion energy was invest igated. The nitrogen content in prepared films increased with decreasing th e nitrogen ion energy, and showed a constant value of 30 at.% below 200 eV. The peak position of Cls spectra as found by X-ray photoelectron spectrosc opy (XPS) analysis shifted to higher binding energy with decreasing nitroge n ion energy. The N1s XPS peak was deconvoluted into three peaks with bindi ng energies BE = 398.3, 400.0 and 402.0 eV, which were assigned to sp(3) C- N and sp(2) C-N and N-N bondings, respectively. The ratio of sp(3) to sp(2) banded nitrogen atoms increased with decreasing ion energy, and showed a m aximum value in the energy interval between 50 and 75 eV. The carbon conten t with the sp3 C-N bond type was estimated at 12.6 at.% from electron energ y loss spectroscopy (EELS) analysis. The nitrogen content with the sp(3) C- N bond type was estimated at 18.0 at-% by XPS. The ratio of carbon to nitro gen atoms with sp(3) bonds was found to be 1.43 in the films grown at nitro gen ion energies of 50 eV, which is close to that of C3N4 compound predicte d as a superhard material. (C) 1999 Elsevier Science S.A. All rights reserv ed.