Growth and Microstructure of Nanoscale Amorphous Carbon Nitride Films Deposited by Electron Beam Irradiation of 1,2-Diaminopropane

The deposition and microstructure of nanoscale nitrogen containing carbon films produced by irradiating adsorbed 1,2-diaminopropane (1,2-DAP) molecules with >40 eV electrons has been Studied, The growth rate of films deposited in the presence of a constant partial pressure of 1,2-DAP was directly proportional to the flux of both precursor 1,2-DAP molecules and the incident electrons, consistent with an electron beam induced deposition (EBID) process. Deposited films were highly textured and weakly adhered to the polycrystalline Au substrate. Complementary information on the electron stimulated decomposition of the precursor and the accompanying film growth was obtained from experiments performed under ultrahigh vacuum (UHV) on nanometer scale thick films of 1,2-DAP. Results from these UHV studies were consistent with the idea that decomposition was initiated by secondary electrons, produced by the interaction of the primary electron beam with the adsorbate layer and the substrate. Reactions of these low energy secondary electrons with adsorbed 1,2-DAP molecules were responsible for dehydrogenation as well as film growth. For prolonged electron exposures nitrile species were produced, supporting the idea that changes in the film's microstructure and chemical composition were due to the effects of C-H and N-H, rather than C-C or C-N, bond cleavage. Collectively, Our results indicate that EBID initially leads to the formation of a hydrogenated carbon nitride (a:C-N(H)) film. Further electron stimulated dehydrogenation ultimately yields an amorphous carbon-nitride film (a:C-N).