Amorphous Silicon Carbon Nitride Films Research Articles

Silicon Carbon Nitride Thin Films Produced by Magnetron Reactive Sputtering Physical Vapour Deposition: Structural, Chemical and Mechanical Characterisation

Amorphous silicon carbon nitride films were deposited on silicon and WC-Co substrates by magnetron reactive sputtering in Ar/N<sub>2</sub> gas mixture with carbon and silicon targets. The influence of experimental parameters on the films morphological, structural and mechanical properties was studied. The general morphology of the film is observed by SEM and TEM. EDXS and FTIR were used to determine the film chemical composition and the nature of chemical bonding. It was observed that C≡N bonds and nitrogen percentage in the film are promoted when the substrate is biased. The role of an underlayer and the influence of its nature on the film adhesion on WC/Co substrates were also studied. In this case, nanoscratch tests showed that a SiNx thin film could be an appropriate underlayer.

Hydrogenated amorphous silicon carbon nitride films prepared by PECVD technology: properties

Hydrogenated amorphous silicon carbon nitride films were grown by plasma enhanced chemical vapor deposition (PECVD) technique. The flow rates of SiH4 , CH4 and NH3 gases were 6 sccm, 30 sccm and 8 sccm, respectively. The deposition temperatures were 350, 400 and 450 ◦C. The RBS and ERD results showed that the concentrations of Si, C, N and H are practically the same in the films deposited at substrate temperatures in the range 350-450 ◦C. In photoluminescence spectra we identified two peaks and assigned them to radiative transitions typical for amorphous materials, ie band to band and defect-related ones. The electrical characterization consists of I(V ) measurement in sandwich configuration for voltages up to 100 V. From electrical characterization, it was found that with increased deposition temperature the resistivity of the amorphous SiCN film was reduced.

Characteristics of thin plasmachemical silicon carbon nitride films deposited using hexamethyldisilane

Silicon carbon nitride (SiCN) coatings are produced by plasma-enhanced chemical vapor deposition using hexamethyldisilane, N2, and H2 as precursors at various nitrogen flow rates (F N). X-ray diffraction data, Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy, adhesion, friction coefficient, abrasive wear resistance, and microprofiling of the film surface are used to characterize the coatings deposited on silicon substrates. The x-ray diffraction analysis shows that all the films have an amorphous structure. The chemical bonding in the films results from the main Si―C, Si―N, and C―N interatomic interactions. With higher $ {F_{{{\text{N}}_2}}} $ , the wear resistance of the films increases and their friction coefficient decreases since Si―C bonds are strengthened. The SiCN films deposited using hexamethyldisilane as the main source material exhibit tribological properties that are comparable with those of amorphous SiCN films deposited using other precursors.

Preparation of Hydrogenated Amorphous Silicon Carbon Nitride Films by Hot-Wire Chemical Vapor Deposition Using Hexamethyldisilazane for Silicon Solar Cell Applications

We propose hydrogenated amorphous silicon carbon nitride (a-SiCN:H) films prepared by hot-wire chemical vapor deposition (HWCVD) using hexamethyldisilazane (HMDS) as a new passivation layer of silicon solar cells. The films deposited at various deposition conditions were characterized focusing on optical properties and passivation quality. We found that the effective lifetime of the samples depended on the amount of Si–H bond and had strong correlation with the interface trap densities. After the optimization, the effective surface recombination velocity of n-type single crystalline silicon (c-Si) (1–10 Ω cm) with a-SiCN:H films has become lower than 60 cm/s and that of p-type was approximately 300 cm/s. The efficiency of a cast polycrystalline silicon solar cell using a-SiCN:H as a passivation layer reached 13.7% (2×2 cm2). Experimental results indicate that a-SiCN:H films are promising low-cost antireflection and passivation layers for silicon solar cells.

Doping and electrical properties of amorphous silicon carbon nitride films

Electrical properties and annealing behaviour of undoped and doped amorphous silicon carbon nitride (a-SiC x N y ) thin films, deposited by ion beam sputtering techniques, have been studied. Doping of the a-SiC x N y thin films with magnesium (Mg), and phosphorous (P) was carried out by ion implantation techniques, and subsequent annealing effect on the electrical conductivity (σ) and activation energies for electrical conduction have been reported. It was found that the undoped films were insulating with electrical conductivities in the range of 10 −6–10 −8 S/cm. Annealing of these films at high temperatures aided in some structural relaxation and hence an increase in σ by several orders of magnitude without showing any indications for crystallization. Suitable doping (Mg) of the films resulted in increased σ, and in some cases of low phosphorous doping a decrease in σ was also found which indicated that the films may be intrinsically p-type.

Effect of dilution gas on SiCN films growth using methylamine

Methylamine (CH 3NH 2) was employed with SiH 4 to deposit amorphous silicon carbon nitride films due to its easy dissociation as well as containing both carbon and nitrogen elements. The effect of dilution gas, such as H 2, N 2, Ar and He on the film growth was studied in electron cyclotron resonance plasma chemical vapor deposition (CVD) reactor. At a microwave power of 250 W and a substrate temperature of 700 °C, ternary silicon carbon nitride film has been successfully deposited using He as dilution gas. However, only binary silicon nitride films were formed using dilution gases of Ar, N 2 and H 2 but otherwise similar conditions. Characterization of the films using FTIR, XPS and optical emission study of the plasma were employed to study the growth process. Possible explanations and discussion for the growth behaviors of the dilution gases are presented.

Structure and elastic properties of amorphous silicon carbon nitride films

Amorphous ${\mathrm{SiC}}_{x}{\mathrm{N}}_{y}$ films with various compositions were deposited by ion-beam sputtering. The bonding characteristics, Young's modulus, and density of the films were investigated using x-ray photoelectron spectroscopy (XPS), Fourier-transform infrared (FTIR) spectroscopy, surface acoustic wave spectroscopy, x-ray reflection, and molecular-dynamics (MD) simulations. It was observed that the Young's modulus decreases from $260\ifmmode\pm\else\textpm\fi{}20$ to $85\ifmmode\pm\else\textpm\fi{}12\mathrm{GPa}$ while the density decreases from $3.45\ifmmode\pm\else\textpm\fi{}0.2$ to $2.3\ifmmode\pm\else\textpm\fi{}0.3{\mathrm{g}/\mathrm{c}\mathrm{m}}^{3}$ as the carbon content of the films increases from 0% to 68%. FTIR and XPS spectra indicate an increasing proportion of double and triple bonds with higher carbon content of the films. These experimental results were compared with the Young's moduli and the infrared spectra obtained from density-functional-based MD simulations. Also for these model calculations the Young's modulus drops from $237\ifmmode\pm\else\textpm\fi{}54$ to $109\ifmmode\pm\else\textpm\fi{}25\mathrm{GPa}$ as the carbon content increases from 0% to 69%. It can be seen that the formation of $\mathrm{C}\mathrm{=}\mathrm{C},$ $\mathrm{C}\mathrm{=}\mathrm{N},$ $\mathrm{C}\mathrm{\ensuremath{\equiv}}\mathrm{C},$ and $\mathrm{C}\mathrm{\ensuremath{\equiv}}\mathrm{N}$ bonds, together with the occurrence of terminating nitrogen atoms for the films with higher carbon content, are responsible for the degradation of the ${\mathrm{sp}}^{3}$ network, and therefore for a lower Young's modulus and density.