Deposition of unhydrogenated diamond-like amorphous carbon films by electrolysis of organic solutions

By electrolysis of organic solutions including methanol, ethanol, 2-propanol, acetone and tetrahydrofuran, an attempt was made to deposit diamond-like carbon (DLC) films on silicon substrates at temperature of less than 60 °C. Substrates were negatively biased with a d.c. potential of 0-3000 V. Among the above electrolytes, only methanol and ethanol give significant results. Fourier transform infrared spectroscopy (FTIR) data show that the O-H, C-H, C-O vibration bands of methanol electrolytes decrease remarkably after electrolysis and a new band characterized as a C=C bond appears. The fact that the deposited films did not contain hydrogen was confirmed by FTIR spectra. The films deposited in methanol and ethanol are DLC films characterized by Raman spectroscopy. The films deposited in methanol are more diamond-like than those of deposited in ethanol under the same experimental conditions.