The role of hydrogen in a-C:H films deposited from hexane or acetylene

Abstract

Present work provides results for amorphous hydrogenated carbon (a-C:H) films deposited by direct ion beam deposition method. Hexane (C6H14) or acetylene (C2H2) precursors and their mixture with hydrogen (H2) were used. The films were characterized by Raman spectroscopy (RS), ellipsometry, IR transmittance and electrical resistance measurements. RS indicated increase of sp3/sp2 bonding ratio and disorder in graphite clusters with increasing hydrogen content (from O to 50% for acetylene precursor) in deposition gas mixture. The opposite trend was observed when the hydrogen concentration exceeds 50% (for acetylene) or additional hydrogen was used (for hexane). The data of electrical resistance measurements supported the correlations defined by RS.