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The elemental composition and the optical properties of hydrogenated amorphous GaAs prepared by r.f. reactive sputtering at different hydrogen and argon pressure and substrate temperature have been determined. From the dependence of the absorption coefficient on photon energy the optical gap has been deduced according to the Tauc law. The data obtained for stoichiometric samples are compared with similar data obtained by different authors. The influence of various deposition parameters on stoichiometry and on the optical properties is briefly discussed.

Optical measurements (UV-visible-NIR) have been performed at room temperature on sputtered a-SiC:H samples after annealing at temperatures, T a , between 673 and 973 K. The complex dielectric constant in the range of 0.8–6.5 eV and, using the Wemple-Di Domenico model, the dispersion energy, the Penn gap, the valence electron density, the plasmon energy and the Fermi energy were deduced. The energy gap was determined by means of various models. The decrease of energy gap and the increase of the valence electron density on one hand, and the shift of the exponential absorption edge on the other hand, indicate the coupling of the valence and the conduction band states by optical photon as the annealing temperature increases. Moreover, as T a exceeds 773 K, the polycrystalline phase can be observed to germinate inside the pre-existing amorphous phase.

The influence of the hydrogen content and its evolution in the annealing treatments of the structural properties of hydrogenated amorphous silicon carbide (a-SiC:H) prepared by plasma enhanced chemical vapour deposition under different deposition conditions have been studied. The results indicate how strongly hydrogen affects the presence of defects in the amorphous network of the samples.

Films of a-SiC:H have been deposited by glow-discharge and annealed at differing temperatures in steps of 50°C in the range 200–450°C. Measurements of elemental composition by means of nuclear techniques, of infrared, photothermal deflection, optical and ESR spectroscopies, of dark and photoconductivity were performed for every annealing temperature. The hydrogen content (free and bonded to silicon and/or carbon), the spin density, the optical gap and the Urbach energy were deduced. By means of differential scanning calorimetry, the annealing behaviour has been interpreted. For annealing temperature lower than 250°C, an irreversible rearrangement of the network has been observed, while over 350°C hydrogen effusion occurs first and then crystallization.

The temperature dependence of the structural properties of a‐SiGe:H and a‐CSiGe:H films has been studied. The samples were characterized by differential scanning calorimetry, conductivity measurements, electron‐spin resonance, infrared, optical, and photoacoustic spectroscopy. The disagreement of previous results of differential scanning calorimetry on hydrogenated amorphous semiconductors samples (a‐Si:H and a‐Ge:H) is examined and discussed. The equilibration temperature determined by the temperature dependence of dc conductivity agrees well with that of the first exothermic process detected with differential calorimetry. The second exothermic effect occurs when hydrogen evolution starts, as confirmed by electron‐spin resonance and infrared spectroscopies.

Results are reported of combined optical and photoacoustic spectroscopy measurements and electron spin resonance measurements (ESR) in binary alloys:a-SixGe1-x:H at different x values and a-CSi:H at different deposition temperatures. Experimental values of optical data and Urbach tails agree very well with a model which takes into account the band gap fluctuations. The densities of spins as obtained by ESR measurements are correlated with the values of integrated absorption in the low energy range.

This paper deals with the metastability of as-deposited a-CSiGe: H alloys. We look essentially at room-temperature dark conductivity of samples, both as deposited and after annealing cycles. Samples were subjected to thermal annealing cycles at increasing temperatures up to around 300°C. The results are analysed from the point of view of the freezing temperature and stretched-exponential structural relaxation. To apply this last analysis, a new approach for non-isothermal relaxation had to be introduced. As a result, the influence of carbon content and deposition temperature upon material metastability has been worked out. Moreover, although hydrogen diffusion is involved in relaxation of a-CSiGe:H, it has been proved that this is not the rate-limiting step of the process.

Spin-resonance spectroscopy has been used to investigate the unpaired spins in a -CSiGe : H alloys prepared by Sputter Assisted Plasmas Chemical Vapour Deposition at different deposition temperatures. Experiments were performed on as deposited and annealed samples. ESR resonances of Ge and Si dangling bonds and an apparently new resonance, which seems to be related to the overlapping of the defect states and the Urbach tail, have been observed on as deposited samples. The corresponding spin density has values higher than those obtained by other authors in binary tetrahedral alloys. A decrease of signals and spin density as the deposition temperature increases and a decrease in samples annealed at 250°C were observed.

The purpose of this paper is to provide a consistent set of data for germanium based alloys using a number of different experimental techniques (optical and photoacoustic spectrometry, Electron Spin Resonance, conductivity and nuclear measurements) in order to know the consequences, both structural and electronic, of carbon incorporation into GeSi network. From correlation between optical and electrical properties information is obtained about the behavior of band tails and the density of states in the gap.

In this letter, the photoluminescence signals in low optical gap (below 2.0 eV) a-C : H : N films were investigated. Films were deposited by r.f. sputtering of a graphite target in ArH2N2 atmospheres having different Ar N 2 flow rate ratios. We have found photoluminescence signals of high intensity and having a peak energy well over 2.0 eV. These results are discussed on the basis of a model in which the sp2 clusters are considered as luminescence centres. Nitrogenation effect upon the luminescence centres and the luminescence intensity correlation with nitrogen concentration are also discussed, in the light of the presented model.

Adherent and transparent unhydrogenated DLC layers were deposited by means of r.f. and d.c. magnetron sputtering at low deposition temperatures. The optical gap value increases from 0.7 to 2.2 eV when deposition pressure is increased from 10 −2 to 10 −1 Torr. In high gap materials, large amounts of sp 3 hybridized carbon atoms are present. When Al contacts are evaporated in coplanar configuration on these high gap materials, rectifying and photoelectrical effects are observed.

In this paper we present the results of a study of the mechanical and thermal properties of hydrogenated amorphous carbon (a-C:H) films. The hardness and Young's modulus of the films show a rough dependence on the sp 3 sp 2 ratio, while the thermal expansion coefficient of the films is a definite function of the sp 3 sp 2 ratio. In fact, it is shown that the thermal expansion coefficient at low temperature (below 130 K) increases with decreasing sp 3 sp 2 ratio. In turn, the thermal conductivity depends on the number of sp3 sites, although further investigations are needed to detail this dependence. The mechanical properties are indirectly correlated with the thermal ones, since both are sensitive to the sp3 amount.

A new method to determine the relative concentration of sp3 and sp2 hybridized carbon through the complex dielectric constant deduced from optical measurements of transmittance and reflectance is reported. In the method a gaussian-like band approximation for π − π* electronic bands is assumed and Wemple-DiDomenico model is applied to obtain thesp3/sp2 ratio. The values of the ratio obtained applying this method are compared with those obtained by IR and NMR spectroscopies.

INTRODUCTION: This study describes a tele-consultation system (TCS) developed to provide a computing environment over a Wide Area Network (WAN) in North Italy (Province of Trento), that can be used by two or more physicians to share medical data and to work co-operatively on medical records. A pilot study has been carried out in oncology to assess the effectiveness of the system. The aim of this project is to facilitate the management of oncology patients by improving communication among the specialists of central and district hospitals. METHODS AND RESULTS: The TCS is an Intranet-based solution. The Intranet is based on a PC WAN with Windows NT Server, Microsoft SQL Server, and Internet Information Server. TCS is composed of native and custom applications developed in the Microsoft Windows (9x and NT) environment. The basic component of the system is the multimedia digital medical record, structured as a collection of HTML and ASP pages. A distributed relational database will allow users to store and retrieve medical records, accessed by a dedicated Web browser via the Web Server. The medical data to be stored and the presentation architecture of the clinical record had been determined in close collaboration with the clinicians involved in the project. TCS will allow a multi-point tele-consultation (TC) among two or more participants on remote computers, providing synchronized surfing through the clinical report. A set of collaborative and personal tools, whiteboard with drawing tools, point-to-point digital audio-conference, chat, local notepad, e-mail service, are integrated in the system to provide an user friendly environment. TCS has been developed as a client-server architecture. The client part of the system is based on the Microsoft Web Browser control and provides the user interface and the tools described above. The server part, running all the time on a dedicated computer, accepts connection requests and manages the connections among the participants in a TC, allowing multiple TC to run simultaneously. TCS has been developed in Visual C++ environment using MFC library and COM technology; ActiveX controls have been written in Visual Basic to perform dedicated tasks from the inside of the HTML clinical report. Before deploying the system in the hospital departments involved in the project, TCS has been tested in our laboratory by clinicians involved in the project to evaluate the usability of the system. DISCUSSION: TCS has the potential to support a "multi-disciplinary distributed virtual oncological meeting". The specialists of different departments and of different hospitals can attend "virtual meetings" and interactively discuss on medical data. An expected benefit of the "virtual meeting" should be the possibility to provide expert remote advice from oncologists to peripheral cancer units in formulating treatment plans, conducting follow-up sessions and supporting clinical research. []

We examine some extensions of the basic model, due to Alur and Dill, of real-time automata (RTA). Our model, controlled real-time automata, is a parameterized family of real-time automata with some additional features like clock stopping, variable clock velocities and periodic tests. We illustrate the power of controlled automata by presenting some languages that can be recognized deterministically by such automata, but cannot be recognized non-deterministically by any other previously introduced class of timed automata (even with ɛ-transitions). On the other hand, due to carefully chosen restrictions, controlled automata conserve basic properties of RTA: the emptiness problem is decidable and for each fixed parameter the family of recognized real-time languages is closed under boolean operations.

In this paper we report a careful analysis of how the composition of a-SIC : H films with optical gap from 2.1 to 2.6 eV deposited by PECVD in SiH4 + CH4 gas mixtures are affected by variations of the molecule dwell time and of the effective dissipated power. We show that variations in the effective dissipated power (from 1.69 to 4.53 W) and in the dwell time (from 0.067 to 1 s) do not change the optoelectronic properties, whose dependence on the optical gap is typical of high electronic quality films deposited in the lower power regime and, also, that these variations lead only to different carbon incorporations in the growing films, without affecting the growth mechanism and the film structure.

Films of a-SiC: H were deposited using an ultrahigh vacuum plasma-enhanced CVD system from SiH4 + CH4 and SiH4 + C2H2 gas mixtures. The compositional, optical, structural and photoluminescence properties of the films were characterized. We have shown that using an acetylene plasma it is possible to grow films having an optical gap in the range 2.3–3.3 eV, high uniformity and high deposition rate. IR spectroscopy revealed remarkable differences in carbon and hydrogen incorporation for the different sources.

In this paper, a set of amorphous carbon nitride (a-C:N) films with different nitrogen contents were analysed. The most relevant deposition parameter is the nitrogen partial pressure, and the role of nitrogen is to reduce the disordered sp 2 phase and the sp 3 sp 2 ratio. The origin of the electron spin resonance active centres is identified to be the disordered sp 2 phase.

The effective dissipated power in SiH 4 -CH 4 -H 2 plasmas excited by 13.56 MHz has been measured for different gas ratios using a subtractive technique to take into account the effects of power losses in the rf circuit. It is found that the dissipated power in general increases with increasing CH 4 concentration and decreases with increasing H 2 concentration. Optical, electrical and defective properties of films deposited under a wide range of deposition conditions have been measured and correlated with dissipated power.

The optical and structural properties of a-SiC:H thin films, deposited by PECVD by using different carbon sources: SiH4 + CH4 and SiH4 + C2H2 gas mixtures, have been characterized by transmittance-reflectance spectroscopy in the range of wavelength 300 - 2000 nm and by IR spectroscopy in the range 400 - 4000 cm-1. By knowing the elemental composition, the results on the physical properties of the films are examined and compared

The dark conductivity of undoped diphasic amorphous-microcrystalline silicon carbon alloy films deposited by plasma-enhanced chemical vapor deposition has been studied as a function of temperature in the range 50–450 K, taking into account their composition, optical and structural properties. From electrical measurements the transport properties were examined and interpreted in terms of a band structure model which includes three mechanisms of carrier transport in different ranges of temperature. The comparison with experiments indicates that the results are consistent with the mechanisms and the model proposed.

AMorphous silicon carbide films were deposited by the PECVD technique in SiH4+CH4 gas mixtures at various CH4 flow rates with and without H2 dilution of the reactive Mixture. A detailed analysis of defect distribution in the gap has been performed by PDS and the results have been correlated with the structural (IR) and the compositional properties (RBS, ERDA). The effect of hydrogen dilution on the electronic properties of the films was investigated by dark and photo electrical conductivity Measurements.

In the present work it is reported a study on ZnO:Al deposited by RF magnetron sputtering of Zn and Al cathodes, or ZnO and Al cathodes in Ar+O2 and Ar atmosphere respectively. In order to obtain high band-gap films transparent in the 300 - 1000 nm wavelength region and highly electrical conductive films, an optimization of the deposition parameters has been performed by the Robust Design Method. ZnO:Al films, with an average transmittance above 85% for about 5000 angstroms thickness and a resistivity of 2 10-3 (Omega) cm have been grown.

We have deposited by Plasma Enhanced Chemical Vapour Deposition (PECVD), under particular conditions of high H2 dilution and high power density, undoped and phosphorus doped (µc‐SiC:H films. We have obtained n‐doped films with a high band‐gap (E04 up to 2.1 eV) and a high dark conductivity (σ4 up to 10 S cm‐1) which are promising materials for window layers in solar cells. Thermo Electric Power (TEP) measurements allowed to identify the type of majority carriers. The dark conductivity and the Hall mobility have been obtained as a function of temperature in the range 80‐480 K.

We report results on a study on μc-Si:H and (μc-SiC:H films deposited by PECVD. The crystallinity fraction and the crystal sizes have been evaluated by X-ray diffractometry, Raman spectroscopy and Transmission Electron Microscopy(TEM). Infrared vibrational spectra of both μc-Si:H and |μc-SiC:H samples have been studied to obtain information on their structure. A comparison between the structure of the amorphous and diphasic amorphous-microcrystalline samples has been performed. Optical properties were obtained by transmission-reflectance and PDS measurements. Electronic transport mechanisms through the conductivity measurements in a wide range of temperatures (50-500 K) have been defined. Structural and electron density models have been discussed and used to interpret the experimental results.

Hydrogenated amorphous carbon (a-C:H) films have been deposited by sputter assisted plasma chemical vapor deposition (CVD). The relative concentration of sp3 and sp2 hybridized carbon in samples is determined by infrared (IR) and nuclear magnetic resonance (NMR) spectroscopies and by a new method through the complex dielectric constant deduced from optical transmittance and reflectance. The results are compared and discussed.

Hydrogenated amorphous carbon thin films have attracted great interest because of their mechanical, electrical and optical properties. Many techniques have been used to produce films with good properties. The present work reports on a comparison between films of high hardness deposited both by glow discharge and sputtering. All the films have been characterized by structural, optical and electrical measurements. Analogies and differences in the structure of the samples obtained by the two methods are discussed.

As a conclusion it can be deduced that in silicon-carbon alloys high optical band-gap can be achieved both in amorphous and in microcrystalline films. In amorphous films the high band-gap is coupled to a difficulty to control electrical properties. In doped films the electrical conductivity ranges from 10-12 to 10-5Ω-1cm-1 with a decrease of optical gap from 2.1 to 1.6 eV. In microcrystalline SiC:H films energy gaps in the range 2 - 2.25 eV have been obtained with dark electrical conductivity from 10-9 to 10-2 Ω-1cm-1. In fluorinated undoped SiC:H,F films energy gaps up to 3.1 eV for amorphous and 2.4 for microcrystalline films have been optained. In such films the conductivity is of the order of 10-9Ω-1cm-1

Single junction a-Si p-i-n solar cells have been deposited by an Ultra High Vacuum (UHV) Multichamber PECVD system reaching an efficiency of 10.1% over 0.1 cm2 and 9.7% over 1 cm2. The effect of hydrogen treatments on the performance of the solar cells was studied on two different types of SnO2 coated substrates and was correlated with the I-V characteristics under AM1.5 (100 mW cm-2) illumination and the spectral response of the devices. The results show that modifications at the TCO/p-layer interface due to the hydrogen plasma treatments are strongly dependent on the initial characteristics of the TCO.

Diamond-like amorphous carbon and hydrogenated amorphous carbon films (DLC) prepared by rf sputtering have been characterized by means of measurements of optical gap, hardness and Young's modulus. Preliminary results of the application of the photothermal displacement technique (PTD) are also reported, confirming that this method can in principle be applied for a more complete characterization of DLC films at room temperature and low temperatures.

Ion implantation of boron and phosphorus in device quality a-SixC1-x:H films deposited by Ultra High Vacuum Plasma Enhanced Chemical Vapor Deposition (UHV PECVD) has been performed. The effects of damage and of damage recovering after annealing were investigated by optical absorption, electrical conductivity and infrared (IR) spectroscopy measurements. It is found that samples doped by phosphorus implantation can have dark conductivities as high as those obtained on samples doped with boron, either by ion implantation or gas phase.

Amorphous and microcrystalline films of silicon and silicon carbide have been deposited by means of PECVD at low substrate temperature (200°C), with reactive gases highly diluted in H2. Devices quality a-Si:H films have been annealed in vacuum at temperatures in the range 200- 1000 °C. The transition from amorphous to crystalline structure was studied by X-ray, Raman and I.R. spectroscopies, optical analysis in UV-VIS-NIR region, Transmission Electron Microscopy, Differential Scanning Calorimetry and Electron Spin Resonance measurements. By comparing the results of the two methods to obtain microcrystalline films we have deduced information on the process of growth of Si and SiC microcrystals.

Amorphous hydrogenated semiconducting films (a-SiC:H and a-CSiGe:H) were studied by means of a power compensation scanning calorimeter and a heat flux quantitative differential thermal analyzer, which work on different principles and have different cell geometry, obtaining for the same sample endothermic andexothermic traces, respectively. An analysis of the reactions has been performed and an interpretation of the antithetical results is given.

Microcrystalline films of SiC.H have been deposited by Plasma Enhanced Chemical Vapor Deposition (PECVD) of SiH4+CH4+H2 mixtures with high power density and high H2 dilution, at variable CH4/SiH4 ratios. Their elemental composition, structural, optical and electrical properties have been investigated in order to evidence the influence of hydrogen and carbon on microcrystallinity.

The purpose of this work is to show that diamond-like carbon (DLC) films of good quality can be deposited by sputtering of a graphite target in an argon-hydrogen atmosphere. The details of the RF diode sputtering system are described. The main features of the deposition process, such as the detection of CH radicals in the plasma, are presented. The advantages of this system are discussed. For example, it joins the easy-to-scale characteristics of the glow discharge process with the independent control of carbon and hydrogen sources found in dual ion beam sputtering. The DLC character of the films are checked measuring the Knupp hardness and the optical energy gap.

A complete set of differential scanning calorimetry (DSC) results for a-Si:H, a-C:H and a-SiC:H, obtained by calorimeters working on different principles and having different cell geometry is reported. DSC curves evidences structural and compositional changes occurring in the films.

There have recently been many experimental and theoretical studies of amorphous carbon (a-C) and hydrogenated amorphous carbon (a-C:H) 1, 2. In a-C, the carbon atoms form both fourfold (sp3) sites (diamond-like) and threefold (sp2) sites (graphite-like).

A new technique based on measurements of photoinduced current noise in amorphous silicon solar cells is reported. A 1/fn (n-1) component, superimposed to a frequency independent one due to simple shot noise, is attributed to the presence of defects limiting the conversion efficiency of the cell. In particular large defects can easily be detected since they are characterized by a very large increase of the l/fn component. In general a correlation is found between the intensity of the l/fn component and short circuit current density, fill factor and cell conversion efficiency.

Experimental results on a systematic investigation on the elemental composition, structural, optical and electrical properties of undoped and doped microcrystalline silicon carbide films deposited by Plasma Enhanced Chemical Vapor Deposition.The doped samples show high values of dark conductivity accompanied by good optical properties so to satisfy the requirements for heterojunction window material.

Boron doped a-SiC:H samples have been obtained both by gas phase doping during film growth and by using ion implantation. All the implanted samples were annealed under vacuum to remove the damage introduced by ion implantation and to produce a dopant diffusion. Physical properties deduced by optical, electrical and structural characterization of the two sets of samples have been compared. Ion implantation technique allows a better control of the dopant dose but increases the compositional disorder and the obtained conductivity values are one order of magnitude lower than those of gas doped samples.

There has been a considerable recent interest in amorphous carbon (a-C) and amorphous hydrogenated carbon (a-C:H) films. These films present a combination of a number of useful properties such as a high value of hardness, transparency to visible radiation over a wide wavelength range and high corrosion resistance. Carbon atoms in these materials have both threefold (sp2) and fourfold (sp3) coordination, and the physical properties are determined by the proportion and distribution of sp2 and sp3 sites1. It is known, for example, that in evaporated a-C sp2 sites are essentially uniformly distributed within the material, whereas in a-C:H these sp2 sites form “islands” which are embedded in a matrix consisting essentially of sp3 sites.

a-SiC:H and a-SiC:H:F films have been prepared by reactive sputtering in mixtures of argon, hydrogen, methane or freon mixtures with different concentrations. The optical and electrical properties, the chemical bonding configuration and the density of defects in these materials have been studied in order to understand how the introduction of F influences the physical properties of the a-SiC random network.

Device-quality films of a-SiC:H deposited by glow-discharge and reactive sputtering have been subjected to annealing treatments in the range 200–800°C in order to study the influence of hydrogen on the evolution of their structural properties. IR, density, optical and electrical measurements contribute to identify the different phase transitions of the network.

Amorphous carbon a-C and amorphous hydrogenated carbon a-C:H films were prepared by rf sputtering of a graphite target in argon and argon-plus-hydrogen atmospheres, respectively. The optical-absorption coefficients of these films were measured by a spectrophotometer in the high-absorption range and by photothermal deflection spectroscopy in the low-absorption range. They were also studied by electron-spin-resonance (ESR) measurements. The optical-absorption spectrum is found to have a rather broad peak, in contrast to the sharp rise in absorption near the band gap observed for normal semiconductors. To explain this broad peak, a model density of states (DOS) for these materials is proposed, in accordance with their well-known microstructure. This consists of a pair of broad Gaussian-like distributions lying above and below the Fermi level and separated by about 4 eV, arising out of the \ensuremath{\pi} states of the aromatic sixfold rings that comprise the bulk of the graphitic ${\mathit{sp}}^{2}$ regions, as well as pairs of discrete levels that are about 0.6 eV apart and are produced by fivefold and sevenfold rings present in these regions. The proposed DOS explains the essential features of the optical-absorption spectra and ESR data. The validity of the concept of the optical gap for these materials is also discussed.

Films of a-SiC:H having different silicon contents have been deposited at room temperature by sputter assisted plasma CVD of a graphite target in a silane — argon atmosphere. The insertion of small amounts of silicon in the a-C:H network yield a material which has mechanical properties similar to DLC and optical gap up to 2.2 eV. The room temperature electrical conductivities are two orders of magnitude higher than typical PECVD deposited hydrogenated amorphous silicon carbide.

Amorphous silicon carbide (a-SiC:H) films deposited by different techniques under different deposition conditions have been submitted to photo-thermal deflection and photoacoustic spectroscopy (PDS and PAS) and electron spin resonance (ESR) measurements in order to obtain, through the trend of low energy absorption coefficient and the density of spins, information on the nature, energy and number of defects. The results obtained from the two techniques are often in disagreement since the dangling bond density generally does not scale with the integrated defect density. In order to explain the discrepancy the absorption coefficient has been calculated, following the Tauc model, in the three regions of fundamental absorption, Urbach tail and excess absorption. An expression for the density of defects has been obtained which depends on the integrated excess absorption coefficient through a proportionality factor.

Electrical noise measurements have been performed on amorphous semiconductor films under irradiation with monochromatic light at different wavelengths. The Power Spectrum Densities (PSDs) of highly photoconductive undoped a-Si:H and a-SiC:H (deposited by glow discharge) in the frequency range .1 – 20 kHz are obtained at room temperature. The analysis is performed upon metal/semiconductor/ITO Schottky barriers. The PSDs vs frequency follow l/fn law and show a change of magnitude when the wavelength of the incident light is varied around the value corresponding to the energy gap.

In order to improve our understanding of the motion of hydrogen and the mechanism by which structural changes occurr, two sets of a-SiC:H samples obtained by glow-discharge at different substrate temperatures and power densities, respectively without and with hydrogen flow, were analyzed.Results from structural, optical and electrical measurements show that annealing and hydrogen diffusion allow for a possible reorganization of the a-SiC:H amorphous network.

Results of a study of compositional, optical, electrical, and structural properties of hydrogen amorphous silicon carbide (a-SiC:H) prepared, respectively, by glow-discharge (GD) and reactive sputtering (SP) techniques at power densities varying between 1.25 · 10−2 and 1.25 · 10−1 W · cm−2 for GD samples are presented. Measurements are reported on the composition, optical and IR spectroscopy, and on the temperature dependence of electrical conductivity. All experimental observations suggest that the power density only slightly affects the physical properties of GD silicon-rich samples, whereas those of the carbon-rich SP samples depend more strongly on this deposition parameter. Finally, it is shown that the GD technique can provide films with better characteristics, whereas samples of similar composition prepared by sputtering have higher compositional disorder and are more inhomogeneous.