AVS 46th International Symposium
    Thin Films Division Monday Sessions
       Session TF+VM-MoA

Paper TF+VM-MoA7
Bonding Structure and Optical Properties of Si-doped Diamond-like Films Synthesized by Plasma Immersion Ion Processing

Monday, October 25, 1999, 4:00 pm, Room 620

Session: Advances in Hard and Superhard Coatings II
Presenter: X.-M. He, Los Alamos National Laboratory
Authors: X.-M. He, Los Alamos National Laboratory
K.C. Walter, Los Alamos National Laboratory
M. Nastasi, Los Alamos National Laboratory
Correspondent: Click to Email
Silicon-doped diamond-like carbon (DLC) films were prepared on Si(100), glass, and PMMA (polymethyl methacrylate) substrates at room temperature by using C@sub 2@H@sub 2@-SiH@sub 4@-Ar plasma immersion ion processing (PIIP) and their compositions were modified by changing deposition parameters of the gas composition and the negative bias voltages applied on the substrates. The influence of the Si dopant on the bonding structure and the properties of the DLC films were investigated by using ion beam analysis techniques, Raman shift, infrared spectroscopy, and by analyzing the measured density and hardness. The electrical and optical properties of Si-doped DLC films have been evaluated by the study of the electrical resistivity, the refractive index, the absorption coefficient, and the optical gap energy for the films. It was found that the variation of Si dopant was highly correlated with the changes of chemical bonding structure and properties. The careful control of gas flow ratio of C@sub 2@H@sub 2@ : SiH@sub 4@ : Ar in low pressure PIIP was needed for the growth of DLC films with optimal combinations of increased sp3 bonding structure, high hardness and density, and improved optical properties. The resultant Si-doped DLC films with a Si content up to 28 at % exhibited a higher optical transmittance in the visible light range. The tribological tests of Si-doped DLC films were carried out using a pin-on-disk tribometer in ambient air at about 15% relative humidity. The results shown that Si-doped DLC films exhibited a low friction coefficient of 0.03-0.08 and an enhanced wear resistance despite of deposition of the films on Si (100), glass, or PMMA substrates. The effects of ion impingement during PIIP deposition on the formation of Si-incorporated DLC films were discussed.