Magnetron Sputtering Of Silicon Research Articles

Fabrication and Properties Study of the Dielectric Membranes Used as Constructive Basis for Sensitive Elements of Gas Sensors

The article presents the properties study results of the dielectric membranes for sensitive elements of semiconductor gas sensors, obtained by different modes of the reactive magnetron sputtering of silicon with application of the two-stage unilateral anisotropic etching of silicon in the organic alkaline solutions. The qualitative analysis of the membranes stability to destructions and deformations in the course of their fabrication and heating is given. Optimum structures and modes of films formation for dielectric membrane structures are determined. The admissible thickness of the thermal silicon oxide underlay, which is does not promote to considerable membranes deformations in the course of their fabrication and heating, is identified.

Coaxial silicon/multi-walled carbon nanotube nanocomposite anodes for long cycle life lithium-ion batteries

Abstract In this work silicon/multi walled carbon nanotube (MWCNT) composite anodes were produced via direct current (DC) magnetron sputtering of silicon onto carbon nanotube papers (buckypapers). The amount of silicon in the composite anodes was varied by using different sputtering powers of 150 W, 175 W, 200 W and the effect on the cell performance was studied. Phase analysis was conducted with X-ray diffraction (XRD) technique and Raman spectroscopy. Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) analyses were employed for morphological characterization of anodes. Energy dispersive spectroscopy (EDS) mapping was used to observe silicon distribution on the buckypapers. Cyclic voltammetry (CV) tests were carried out to reveal reversible reactions between silicon and lithium. Galvanostatic charge/discharge technique was employed to determine the cyclic performance of anodes. Electrochemical impedance spectroscopy technique was used to understand the relation between cyclic performance and internal resistance of cells. The results showed capacity retention of silicon anodes was improved with composite structure and higher capacity values were achieved than graphite anodes. The silicon/carbon nanotube composite produced with 150 W showed the best cycle stability after 100 cycles of galvanostatic charge/discharge tests with capacity value of 620 mAh g−1.

Microstructure of silicon-incorporated carbon films with various silicon concentrations deposited by hybrid magnetron sputtering/chemical vapor deposition

Abstract A hybrid technique combining the radio-frequency magnetron sputtering of silicon and the plasma-enhanced chemical vapor deposition of hydrogenated carbon was developed to synthesize silicon-incorporating diamond-like carbon films. Plasma power was supplied at different levels to a silicon electrode in an Ar/CH4 atmosphere to prepare films having different Si contents. The effects of plasma power level on the compositions and microstructures of the deposited film were investigated. The Si contents and deposition rates of the films increased with the plasma power. All the films exhibited an amorphous structure. The addition of Si not only resulted in the smoothening of the granular surfaces of the films but also led to the formation of round projections having a diameter of about 200 nm on the surfaces. Most of the Si in the films reacted with carbon, and no precipitation of SiC or Si phases was noticed in the films.

Raman Spectroscopy of Carbon Based Films – Spectra Interpretation and Selected Applications

The investigation of the film structure of diamond-like carbon films was the main objective of this work. Films within the structural systems of hydrogenated tetrahedral amorphous carbon (ta-C:H), silicon doped hydrogenated amorphous carbon (a-C:H:Si) and nitrogen doped amorphous carbon (a-C:N) were deposited at substrate temperatures of well below 100 °C. As deposition methods ion beam deposition, reactive unbalanced magnetron sputtering of silicon as well as infrared pulsed laser deposition (IR-PLD; λ=1064 nm) were studied. By the use of Raman spectroscopy it was found, that for high kinetic ion energy film deposition processes, i.e. ion beam deposition, the structure and properties of the ta-C:H films can be controlled by the kinetic energy of carbon species involved during film growth. For deposition techniques being typically known for low ion energies like magnetron sputtering or IR-PLD, applied for deposition of a-C:H:Si and a-C:N films, process tuning involves the study of the effects of inert gas/ reactive gas flow and the type of the reactive gas.

The influence of vacuum annealing temperature on the fundamental absorption edge and structural relaxation of a-SiC:H films

The effect of vacuum annealing temperature on the characteristics of the fundamental absorption edge and short-range order reconstruction in amorphous hydrogenated silicon carbide (a-SiC:H) films obtained by magnetron sputtering of silicon in an Ar/CH4 mixture is experimentally investigated. It is shown that redistribution of chemically bound hydrogen occurs at low annealing temperatures (450°C). This redistribution is determined by (i) breakage of silicon-hydrogen bonds and (ii) trapping of atomic hydrogen by carbon dangling bonds. These processes lead to an enhancement of visible photoluminescence. Breakage of carbon-hydrogen bonds and clusterization of amorphous carbon occur at higher annealing temperatures. The proposition that the main nonradiative recombination centers in a-SiC:H films are electronic states related to the carbon dangling bonds is justified.

Crystalline SiC thin films deposited at room temperature using pulsed laser ablation of graphite and magnetron sputtering of silicon

Crystalline SiC films are typically deposited on substrates at elevated temperatures by sputtering, pulsed laser ablation, thermal chemical vapor deposition (CVD) and CVD plasma assisted. However, high temperature may adversely affect the substrate, especially when metal alloys are used. To maintain substrate properties (temper, dimensional tolerance, etc.), a low deposition temperature is required. In this work, silicon carbide is formed from simultaneous sputtering of silicon and laser ablation of graphite onto suitably biased substrates at room temperature. The advantage of this method lies in the independent selection of plasma characteristics of both magnetron sputtering and laser ablation to achieve the required stoichiometry and species energetics. Desirable film properties such as good adhesion and crystallinity normally requiring elevated substrate temperatures are obtained via the energetic bombardment of the growing film. In this study, films are grown on M50 steel substrates at biasing varied from 0 to −300 V permitting control over crystallinity, chemistry, and stoichiometry. X-ray photoelectron spectroscopy (XPS) analysis shows the existence of silicon carbide bonds and x-ray diffraction analysis demonstrated the growth of crystalline (prominently alpha polytypes (4H–SiC, 6H–SiC) films at room temperature. In addition, XPS is used to find percentage of SiC bonds in the films. The optimum bias −100 V was found to favor crystalline growth in these films. Special emphasis is given to control of film stoichiometry as it relates to mechanical properties.

Modification of Magnetron Sputtered A-Si1-Xcx:H Films by Implantation of sn+

AbstractImplantation of Sn+ into a-Si1.xCx:H films deposited by RF magnetron sputtering of silicon and graphite was carried out in order to obtain optical contrast in the layers. The expected optical effect which is an absorption edge shift to the lower photon energies accompanied by a considerable increase of the absorption coefficient was observed even for the lowest dose - 1015cm-2. This effect is more pronounced with increase of the dose. Infrared (IR) and photoelectron spectroscopy (XPS) measurements was used to study the bond configurations of implanted films. These measurements reveal that ion implantation introduces an additional disorder in the films as well as leads to their chemical modification, which could be related to the changes of the optical properties.

Improvement of photoconductivity of a-SiC:H films by introducing nitrogen during magnetron sputtering process

Nitrogen has been introduced in the preparation of hydrogenated amorphous silicon carbon alloy films by magnetron sputtering of silicon in a methane-argon gas mixture. The partial pressure of nitrogen was changed, and its effects on the structural, optical, electrical, and optoelectronic properties of the deposited films were investigated. The SiN bond becomes predominant with increasing partial pressure of nitrogen pN above 10%, at which the optical band gap is rapidly increased. The concentration of silicon and carbon in the films remained almost unchanged by changing pN up to 20%. It was found that the photoconductivity is also almost unchanged up to 20%, while the optical band gap is increased. This indicates that the photoconductivity is improved over a wider optical band gap, as compared with previous studies when the optical band gap was changed by changing deposition conditions but without introducing nitrogen.

Electron spin resonance of hydrogenated amorphous silicon-carbon alloy films prepared by magnetron sputtering

Abstract New electron spin resonance (ESR) lines with g1 = 2·0017 and g2 and g3 = 2·0006 have been found in the ESR spectra of as-deposited a-Si1–x Cx:H films prepared by magnetron sputtering of silicon in the gas mixtures of methane and argon. Similarities between the observed spectra and those for the E′ centre in glassy SiO2 are discussed.

Properties of hydrogenated and fluorinated amorphous silicon–carbon alloy films prepared by magnetron sputtering

Abstract Hydrogenated and fluorinated amorphous silicon-carbon alloy films have been prepared by magnetron sputtering of silicon in Ar–CH4–CF4 gas mixtures. The dependence of compositional, structural, optical and optoelectronic properties of the films on the ratio R H of the partial pressure of CH4 to the total gas pressure and the corresponding ratio R F for CF4 have been investigated. It is found that (i) the optical band gap as well as the activation energy of the dark conductivity is controllable, (ii) SiC bonds are formed easily and (iii) the photoconductivity is improved by about one order of magnitude, compared with the films prepared using Ar-H2-CF4 gas mixtures reported previously. In addition, several kinds of extrema against R H were observed in such quantities as the room-temperature photoconductivity, the edge-width factor B in the optical absorption spectrum, and the activation energy of the photoconductivity. In the films having these extrema, the AM1 photoconductivity and photosensitivity...

Effect of hydrogen on the properties of magnetron sputtering of hydrogenated amorphous silicon carbon alloy films

Hydrogenated amorphous silicon carbon alloy films have been prepared by magnetron sputtering of silicon in methane-hydrogen-argon gas mixtures, and the dependence of film properties on hydrogen partial pressure (PH) as well as methane partial pressure against total gas pressure has been investigated. With increasing PH, the concentration of carbon increases, accompanied with the increase in the number of Si–C bonds, in spite of the unchanging partial pressure of methane. Following this, the optical band gap and activation energies of dc conductivities increase, and the photoconductivity as well as the dark conductivity decreases. The intensity of Si–H bonds is almost unchanged, while that of C–H bonds increases. These results are discussed mainly from the standpoint of the change of deposition process composed of the chemical decomposition of methane and the physical sputtering of silicon.

ＣＨ４を用いたマグネトロンスパッタ法によって作製したアモルファスＳｉＣ：Ｈ薄膜の作製条件依存性

Amorphous SiC : H alloy films were prepared by magnetron sputtering of silicon in methane-argon gas mixtures.The influence of the deposition conditions, such as rf power (50-200W), sputtering pressure (4-70 mTorr), and substrate temperature (300-450°C) on the properties of the prepared films were extensively investigated. With decreasing rf power below 100 W or increasing sputtering pressure above 30 mTorr, the optical band gap and the activation energy of dark conductivity increased accompanied by an increase of the amount of Si-C bond. Moreover, it was found that the dark conductivity as well as the photoconductivity increased with increasing rf power, and they revealed the maxima at 10 mTorr in sputtering pressure. Several characteristics concerning the preferential attachment of hydrogen to carbon, and the conduction band tail width were also examined, and were discussed from the standpoint of the structural and compositional change of the films correlating with deposition conditions.

Influence of sputtering pressure on the properties of hydrogenated amorphous-silicon carbon alloy films prepared by magnetron sputtering of silicon in methane-argon gas mixtures

The structural, optical, electrical, and optoelectronic properties of magnetron sputtered hydrogenated amorphous-silicon carbon alloy films have been investigated as a function of sputtering pressure. The optical band gap, the activation energy of dark conductivity, and concentration of hydrogen increase with increasing sputtering pressure. The photoconductivity as well as the dark conductivity shows a maximum against pressure. These results are discussed from the standpoint of the structural and compositional change of the films with sputtering pressure, originating from the change of plasma reaction process composed of the decomposition of methane and the sputtering of silicon.

Influence of rf power on the properties of hydrogenated amorphous silicon carbon alloy films prepared by magnetron sputtering of silicon in methane-argon gas mixtures

The rf power dependence of structural, optical, electrical, and optoelectronic properties of hydrogenated amorphous silicon carbon alloy films prepared by magnetron sputtering of silicon in methane-argon gas mixtures has been investigated. With increasing rf power, the optical band gap and the activation energy of dark conductivity decrease, accompanied by a decrease in the concentration of Si-C bonds. The dark conductivity and the photoconductivity increase with increasing rf power. These results are discussed in terms of the compositional and structural change of the films with rf power, such as the factor of preferential attachment of hydrogen to carbon deduced from IR measurements, and the conduction-band tail width deduced from optical absorption spectra or from temperature dependence of photoconductivity.

Structural, optical and electronic properties of amorphous SiC: H alloys prepared by magnetron sputtering of silicon in methane-argon gas mixtures

Abstract Amorphous Si1−x C x :H films have been prepared by the r.f. magnetron sputtering method using a silicon target in a gas mixture of argon and methane. The carbon content x was varied by varying the partial pressure of methane with respect to the total gas pressure. The dependence of the optical, structural and electrical properties on x has been investigated. With increasing x, the optical band gap increases owing to the hydrogenation of silicon in the region of small x and to the increase in the number of Si-C bonds in the large-x range, according to evidence from infrared spectra. While the dark conductivity decreases with increasing x, the photoconductivity shows a maximum at about x = 0·2. The photoconductivity increases in the range of x below 0·2 owing to the hydrogenation of silicon. Although it decreases in the range of x above 0·2, the values are larger than those of films prepared by glow-discharge decomposition of methane-silane gas mixtures reported in the literature. This is interpret...

Highly photoconductive and photosensitive hydrogenated amorphous silicon carbon alloy films prepared by magnetron sputtering

Undoped hydrogenated amorphous silicon carbon alloy thin films were prepared by the magnetron sputtering of silicon in a gas mixture of methane argon. It is found that the photoconductivities of the films with carbon concentration above 15% are one order of magnitude or more larger than the films prepared by the glow discharge decomposition of silane-methane gas mixture reported by other groups before now. Moreover, the photosensitivities of these films are larger than those of the glow discharge films, as a result of small dark conductivities of the former compared with those of the latter.