Silicon-carbon thin films deposited by excimer lamp CVD from disilane and ethylene.

Amorphous hydrogenated silicon-carbon layers have been prepared from disila ne and ethylene precursors by Xe-2* excimer lamp induced-chemical vapour de position. The influence of the substrate temperature, in the range between 100 degrees C and 300 degrees C, on the film properties has been determined by different characterization techniques. Ellipsometric measurements give film growth rates between 0.9 and 2.1 nm/mi n, and refractive index values following an increasing tendency with temper ature from 2.3 to 3.9. The band gap was calculated from the optical absorpt ion measurements, exhibiting a linear decreasing tendency with the substrat e temperature from 2.5 to 1.7. Films produced from these precursors present high silicon concentration, as determined by Rutherford Backscattering Spe ctroscopy, the Si content being increased with the temperature of the subst rate. The chemical structure was determined by infrared and Raman spectrosc opies, from which analyses are deduced the presence of SI-C, C-C and Si-Si bonds and also hydrogen bonded to silicon and carbon atoms. Interpretation of the changes induced by the temperature in the structure and macroscopic properties of the films are also discussed. (C) 1998 Elsevier Science Ltd. All rights reserved.