Low temperature direct growth of nanocrystalline silicon carbide films

Hydrogenated silicon carbide thin films have been grown directly by reactiv e magnetron co-sputtering of Si and C targets in a purr hydrogen plasma at substrate temperatures, T-s. ranging between 300 and 700 degrees C. The res ults reveal the achievement of nanocrystalline SiC at a deposition temperat ure of 400 degrees C, the lowest temperature ever reported for the sputteri ng method. Both intensity increase and peak narrowing of the lorentzian inf rared absorption band at similar to 800 cm(-1) ascribed to Si-C bonds in th e crystalline state, are indicative of the continuing improvement of the cr ystallinity when T-s is increased beyond 400 degrees C. According to the X- ray photoelectron spectroscopy (XPS) measurements, the SiC layers are carbo n rich with an atomic ratio C/Si approaching 1.15 for T-s approximate to 40 0-600 degrees C. The Si atoms are found. however, tetracoordinated with onl y the C atoms, in perfect agreement with the Raman data that exclude the fo rmation of amorphous or crystalline Si, even though they report the presenc e of excess carbon. The high resolution electron microscopy observations cl early indicate the formation of randomly oriented SiC crystals of the cubic phase at T-s greater than or equal to 400 degrees C with an average size o f a few nanometers. (C) 2000 Elsevier Science S.A. All rights reserved.