Papers by Keyword: RBS

Abstract: ZnO waveguide films were fabricated on sapphire (001) and MgO (100) substrates by the radiofrequency (RF) magnetron sputtering technology using ZnO ceramic as the target. Properties of the films were investigated by prism coupling method, X-ray diffraction (XRD) and Rutherford backscattering spectrometry (RBS). The results demonstrated that the ZnO nano-films have planar waveguide structure and have nearly stoichiometric composition with c-axis preferred orientation growth. The growth rates of the films were slightly influenced by the substrates. The effective refractive indices of the films were smaller than the bulk material and were affected by substrates. The relationships between the average grain sizes, substrates, and film thickness were analyzed.

Abstract: The composition of an annealed ternary system is examined by combined ion beam analysis (standard RBS & nuclear microprobe PIXE), SEM (morphology & EDS) and also with XRD to get the elemental composition and distribution over particular micro regions. The ternary system is built by the superposition of two metal layers, Gold and Copper respectively, both having 1200 Å in thickness, successively deposited on a (111) monocristalline silicon substrate. Then, the whole system is subjected to a vacuum heat treatment (at 400°C during 30 min). The enhanced interdiffusion and the arisen transformations are evidenced [8]. The investigations are particularly, emphasized on the induced Copper Silicide. A mapping of the elemental distribution, over restricted area is provided by micro-PIXE using the method of Dynamic Analysis as well as the corresponding Geo-PIXE II Software package. On the other hand, a special web network likewise is realized by performing several EDS punctual analysis, strictly focused on the formed phase site resulting in a well defined planar zoning of the elemental distribution.

Abstract: Tantalum oxynitride thin films are deposited by radio-frequency magnetron sputtering using a pure tantalum target under argon/oxygen/nitrogen gas mixture. The argon flow is kept constant while the oxygen and nitrogen flows are changed simultaneously in a way to keep constant the total flow of these reactive gases. We succeed to deposit TaO_xN_y films with stoichiometry ranging between those of TaN and Ta₂O₅. All films are deposited at room temperature and are amorphous. Spectroscopic ellipsometry and UV-visible spectrometry investigations show a direct relation between the optical properties and the stoichiometry of the films. In particular, the results show a variation of the refractive index from pure tantalum nitride-like films (3.76) to tantalum pentoxyde-like films (2.1), which confirms the possibility to deposit graded antireflective coatings with tantalum oxynitride.

Abstract: Carbon nitride films were synthesized by pulsed laser ablation of graphite target under nitrogen ambience. The third harmonic of a pulsed Nd-YAG laser of 355 nm wavelength and 7 ns pulse duration was focused onto a rotating target at an incidence angle of 45°. The laser fluence at the target surface was set at 30 J/cm2. The carbon nitride films were deposited on (100) silicon substrate kept at room temperature and placed at a distance of 40 mm from the target surface. The CNx films were grown under N2 gas in the pressure range of 5×10-3 to 4×10-1 mbar. The deposited films composition was investigated by different techniques RBS, NRA and AES. We found an N/C ratio equal to 0.4 in the pressure range cited above.

Abstract: Wireless sensor network applications often require a scalable time synchronization with the environment and communicating. Most of time synchronization algorithms are based on hierarchical structure and the precision is promoted at the expense of more complicated calculation. At the same time, the time synchronous is slower on the whole network because of the worse channel collision. This paper presents a novel time synchronization algorithm on the basis of synchronizer of clustering architecture. We adopt the improved RBS approach and introduce the synchronizer as to reducing messages’ overhead efficiently. Finally, performance of this algorithm is illustrated by a simulation experiment.

Abstract: The ternary system has been built by the deposit of two metal coats (layers), Gold and Palladium on a monocrystalline Silicon substrate of orientation (111). The whole system has been subjected to a vacuum heat treatment, the range of temperatures starts from 100 °C up to 600°C by steps of 50°C and with an annealing time being fixed at 30 min. Both metal layers were successively deposited without breaking the vacuum within the evaporator. The Silicon substrate had undergone beforehand a chemical treatment by the method in the CP4 to prevent it from the Oxygen barrier effect. So, we obtained few series of samples of which the characterization has been carried out by various techniques, namely: the spectroscopy of retrodiffusion of Rutherford (RBS), the diffraction of the X-rays (XRD), the scanning electronic microscopy (SEM) and its incorporated technique of Energy Dispersive X-rays (DEX). These analyses allowed us to fulfil a study of the interdiffusion

Abstract: Metal impurities are known to degrade dramatically the performances of silicon-based devices, even at concentrations as low as 1012 cm-3. A specific process, named proximity gettering, has been optimised by some authors in order to reduce the influence of these impurities [1]. This process consists in the building of a favourable impurity trapping zone in a non-active area of the device, by introducing implantation defects. This paper reports on the application of introducing such gettering sites as an approach to control phonon properties in 4H-SiC epilayer, and increase the thermal conductivity.

Abstract: The Zn-Se bilayer structure prepared using thermal evaporation method at pressure 10-5 Torr. These films annealed in the vacuum for two hours on different constant temperatures. The optical band gap was found to be varying with annealing temperature due to removal of defects and increase in grain size. It was also observed by the X-ray diffraction pattern the grain size of the film increase with annealing temperature. The lattice constant of hexagonal structure of these films is found to be a =b=4.42Å and c=5.68Å. The dominant peaks to be at 23.2°,28° and 43.9° having values (100), (002) and (111) respectively. The Rutherford back scattering data of these films confirmed the mixing of elements with time.

Abstract: Thin SiN film deposited on Si by plasma enhanced chemical vapour deposition (PECVD) is used for surface passivation of Si. During the PECVD process Hydrogen is incorporated into the SiN film, and the passivation properties of the resulting SiNx:H layers play an important role in enhancing the energy conversion efficiency of solar cells. It is believed that the Hydrogen present in SiNx:H is responsible for this enhancement, and therefore its concentration in the passivating layer is an important parameter. The Hydrogen composition and its depth profile in thin SiNx:H films of 20nm to 200nm was measured by elastic recoil detection analysis (ERDA), using a 1.7MeV He+ ion beam of (1x2)mm2, generated by a high stability 2MV Tandetron ion beam accelerator. Simultaneously, Rutherford backscattering (RBS) spectra were recorded for each sample. The results show that the Hydrogen concentration in the SiNx:H layers is dependent of the deposition conditions. Also, Hydrogen was found to be homogenously distributed across the SiNx:H layer thickness, and the SiNx:H/Si interfaces were well defined.

Abstract: In this paper we present a study of the formation of TiN thin films during the IBAD process. We have analyzed the effects of process parameters such as Ar+ ion energy, ion incident angle, Ti evaporation rates and partial pressure of N2 on preferred orientation and resistivity of TiN layers. TiN thin films were grown by evaporation of Ti in the presence of N2 and simultaneously bombarded with Ar+ ions. Base pressure in the IBAD chamber was 1⋅10-6 mbar. The partial pressure of Ar during deposition was (3.1 – 6.6)⋅10-6 mbar and partial pressure of N2 was 6.0⋅10-6 - 1.1⋅10-5 mbar. The substrates used were Si (100) wafers. TiN thin layers were deposited to a thickness of 85 – 360 nm at deposition rates of Ti from 0.05 to 0.25nm/s. Argon ion energy was varied from 1.5 to 2.0 keV and the angle of ion beam incidence from 0 to 30o. All samples were analyzed by Rutherford backscattering spectrometry (RBS). The changes in concentration profiles of titanium, nitrogen and silicon were determined with 900 keV He++ ion beam. The RBS spectra were analyzed with the demo version of WiNDF code. We have also used X-ray diffraction (XRD) for phase identification. The resistivity of samples was measured with four-point probe method. The results clearly show that TiN thin layer grows with (111) and (200) preferred orientation, depending on the IBAD deposition parameters. Consequently, the formation of TiN thin layers with wellcontrolled crystalline orientation occurs. Also, it was found that the variations in TiN film resistivity could be mainly attributed to the ion beam induced damage during the IBAD process.