Thermal stability of amorphous carbon films grown by pulsed laser deposition

2019-10-10 12:28:02

temperature TC films laser Raman

责任者: Friedmann, T.A.;McCarty, K.F.;Barbour, J.C.;Siegal, M.P.;Dibble, D.C. 单位: Sandia Nat. Labs., Albuquerque, NM, USA 来源出处: Applied Physics Letters(Appl. Phys. Lett. (USA)),1996/03/18,68(12):1643-5 摘要: The thermal stability in vacuum of amorphous tetrahedrally coordinated carbon (a-tC) films grown on Si has been assessed by in situ Raman spectroscopy. Films were grown in vacuum on room-temperature substrates using laser fluences of 12, 22, and 45 J/cm2 and in a background gas of either hydrogen or nitrogen using a laser fluence of 45 J/cm2. The films grown in vacuum at high fluence (>20 J/cm2) show little change in the a-tC Raman spectra with temperature up to 800°C. Above this temperature the films convert to glassy carbon (nanocrystalline graphite). Samples grown in vacuum at lower fluence or in a background gas (H2 or N2) at high fluence are not nearly as stable. For all samples, the Raman signal from the Si substrate (observed through the n-tC film) decreases in intensity with annealing temperature indicating that the transparency of the a-tC films is decreasing with temperature. These changes in transparency begin at much lower temperatures (~200°C) than the changes in the a-tC Raman band shape and indicate that subtle changes are occurring in the a-tC films at lower temperatures 关键词: amorphous state;annealing;carbon;pulsed laser deposition;Raman spectra;thermal stability;thin films;transparency;amorphous films;pulsed laser deposition;thermal stability;tetrahedrally coordinated films;in situ Raman spectroscopy;nanocrystalline graphite;Si substrate;annealing temperature;transparency;800 degC;200 degC;C;Si