Papers by Keyword: Film Composition

Abstract: The effects of carbon content on the piezoresistive properties of non-stoichiometric silicon carbide (SixCy) films deposited on thermally oxidized (100) Si substrates by Plasma Enhanced Chemical Vapor Deposition (PECVD) from silane (SiH4) and methane (CH4) gas mixtures have been investigated. Four different film compositions have been obtained by varying SiH4 flow ratios from 1.0 to 4.0 sccm, while the other parameters were kept constant. In order to evaluate the piezoresistive properties of the SixCy films, we have developed test structures consisting of SixCy thin-film resistors defined by reactive ion etching (RIE) with Ti/Au pads formed by lift-off process. The gauge factor (GF) and temperature coefficient of resistance (TCR) of each SixCy film were measured.

Abstract: 82% Ni-Fe films have been prepared using Radio frequency (R.F) sputtered, R.F induced substrate bias. The results presented are of study of sputter films deposition at various RF substrate bias conditions so that suitable sputtering rate with optimum (target) composition could be determined for magnetoresistive sensing applications. Films have been sputtered with substrate temperature of 200^° C, sputter gas (argon) pressure of 10mTorr with film thicknesses near 1000 ^°A. Substrate bias potential in the range 0 V to -400 V is varied in order to determine its dependence upon film composition and deposition rate. The result presented indicates the strong bias dependence upon film composition and deposition rate with most useful films for the application in concern could be produced at substrate bias potential in the range of -80 V to -120 V.

Abstract: Titanium dioxide (TiO2) thin films were deposited by rf magnetron sputtering, using a Ti target (purity 99.99%), on poly (ethylene terephthalate) (PET) substrate. Argon and oxygen were used as the working and reacting gas, respectively. The surface morphology was studied using scanning electron microscopy (SEM) and atomic force microscopy (AFM), and the film composition and structure by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). Uniform and compact TiO2 nanoparticles with diameter about 50 nm were deposited on PET substrates within 2 minutes. Many nano-sized particles aggregated and formed larger clusters after 5 minutes. The size of the clusters increased with increased sputtering time. The particles grew perpendicular to the substrate, and the surfaces of the films were smooth and undulate. The Ti2p peak was resolvable into the three valence species Ti4+, Ti3+ and Ti2+. The O/Ti ratio varied with the Ar: O2, ratio, the optimum value of which was in the range 4-8. The TiO2 films deposited on PET substrate were amorphous.

Abstract: Combined amorphous and nanocrystalline films attract an attention due to possibility to improve toughness, wear resistance and other properties which are important in nanomaterials and processes in energy systems. One of the known film fabrication methods is the magnetron sputtering deposition in the presence of an additional external magnetic field with inductions of up to 0.3 T as it was demonstrated by an example of the B4C-TiB2 system. The induction effects on the amorphous films hardness, growth rate and nanocrystallization process were investigated and discussed. The deposition under an additional external magnetic field with induction more than 0.2 T leads to the of nc-inclusions formation as was determined by X-ray diffraction, microdiffraction and high resolution transmission electron microscopy methods. The target and film compositions were determined by energy disperse spectroscopy and Rutherford backscattering spectroscopy. Compared to the target composition, some enrichment by nonmetallic elements (carbon and boron) was fixed in films.