In this study, we have employed infrared (IR) absorption spectroscopy, visible Raman spectroscopy, and x-ray absorption near edge structure (XANES) to quantify the hydrogen (H) content in hydrogenated amorphous carbon (a-C:H) films. a-C:H films with a hydrogen content varying from 29 to 47 at. % have been synthesized by electron cyclotron resonance chemical vapor deposition at low substrate temperatures (< 1 2 0 °C) applying a wide range of bias voltage, Vb, (-300 V < Vb < +100 V). With the application of high negative Vb, the a-C:H films undergo a dehydrogenation process accompanied by a sharp structural modification from polymer-to fullerenelike films. The trend in the H content derived from elastic recoil detection analysis (ERDA) is quantitatively reproduced from the intensity of the C -H bands and states in the IR and XANES spectra, respectively, as well as from the photoluminescence (PL) background drop in the Raman spectra. Using the H contents obtained by ERDA as reference data, semiquantitative expressions are inferred for the amount of bonded hydrogen as a function of the experimental spectroscopic parameters, i.e., the integrated area of the IR C -H stretching band at about 2900 cm-1, the PL background in visible Raman spectra, and the XANES intensity of the o-*-CH peak.

This paper deals with optical emission spectroscopy studies of low pressure (0.1-0.5 Torr) capacitively coupled radiofrequency hydrocarbon/argon-rich plasmas used for the synthesis of nanocarbon structures. The main goal of this paper is to obtain the electron temperature of such far-from-equilibrium plasmas as a function of the pressure, the excitation power and the argon content. In doing so, we have found that the argon upper energy levels used for electron temperature estimation remain close to corona balance. The latter has allowed us to use a modified Boltzmann plot technique to derive the electron temperature. It was found that, for the plasmas investigated, an increase of the argon population density (from 10% to 95%) leads to a pronounced decrease of the electron temperature while an increase of the processing pressure produces a moderate increase of the electron temperature. Additionally, the increase of the power from 50 to 300 W produces a very slight growth of the electron temperature.

We have studied the growth dynamics of ultrasmooth hydrogenated amorphous carbon films deposited on silicon substrates by electron cyclotron resonance chemical vapor deposition from argon/methane gas mixtures applying a high negative external bias. The surface morphology of films deposited for different growth times under the same experimental conditions was analyzed by atomic force microscopy. Our analysis leads to values of the growth, roughness, and coarsening exponents of 0, 0.1, and 0.5, respectively. As it has been recently proposed that the growth dynamics of amorphous films by ion-assisted methods should obey the Edwards-Wilkinson ͑EW͒ growth mode, we have analyzed the compatibility of our data with this model. Our analysis indicates that, although the scaling data could be interpreted in terms of the EW model, the relative large data error bars and the film ultrasmoothness preclude the unambiguous assessment of the EW growth mode for our film growth evolution. In our system, the interplay of shadowing, physical sputtering and enhanced surface mobility ion-induced effects contribute likely to the leveling and final ultrasmoothness of the film surface.

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