MICROSTRUCTURE AND PHYSICAL-PROPERTIES OF IRON CARBIDE FILMS FORMED BY PLASMA-ENHANCED CHEMICAL-VAPOR-DEPOSITION

We report the structure and properties of iron-containing films deposi ted on glass substrates maintained at temperatures between 200 and 500 degrees C. The films investigated were Fe3O4, Fe7C3, Fe3C, and alpha- Fe, deposited at substrate temperatures of 200, 300, 400 and 500 degre es C, respectively. The measured SEM grain sizes from these 200-700 nm thick films were in the 50-350 nm range. X-ray diffraction and scanni ng electron microscopy show larger grains and increased crystallinity in the films deposited at higher substrate temperatures. The larger gr ain sizes and increased crystallinity are consequences of bulk diffusi on and surface recrystallization. The sheet conductivities of the film s increase with increasing film deposition temperature, due to coarser grain structures and higher iron to carbon ratios in the higher tempe rature films. The phases remain unchanged after annealing at 400 degre es C for 4 h. X-ray diffraction and scanning electron microscopy show evidence of bulk rearrangement and a reduction of thickness in the ann ealed films.