Interdependence of structural and electrical properties in tantalum/tantalum oxide multilayers

Abstract

Dc reactive sputtering was used to deposit tantalum metal/oxide periodic nanometric multilayers using the innovative technique namely, the reactive gas pulsing process (RGPP). Different pulsing periods were used for each deposition to produce metal-oxide periodic alternations included between 5 and 80 nm. HighlightsDc reactive sputtering was implemented with the reactive gas pulsing process.Combination of the structural analyses allowed determining the composition of different phases.HRTEM pointed out the dependence between electrical properties and nanometric and periodic Ti/fcc-TiO/a-TiO 2 multilayers.

Using of Magnetron Sputtering for Biocompatible Composites Creating

“…In case of thin films of tantalum, according to literary data, formation of both alpha and beta phases, which differ in properties, is possible [10][11][12][13][14][15][16][17][27][28][29]. The X-ray diffraction patterns of our samples with nitinol basis (Figure 3) demonstrate that depending on sputtering, time tantalum is formed in two various crystal states-an alpha (a cubic crystal lattice) and a beta (a tetragonal lattice with the small content of oxygen).…”

“…It is noted that the alpha phase is formed at temperatures more than 400°C, promoting mobility increase in deposited atoms : initially at heating of a substrate or as a result of the annealing following sedimentation (then deposited β-Ta transforms in α-Ta ) [ 10,14,27,28]. However at a temperature about 400-500°C, β phase is also received (for example, in the form of the particles distributed in α) [10,28], and α is also formed without heating [12,15]. It is specified that with the growth of temperature, the size of grains, impurity amount in a surface layer (for example, the dissociation of oxides enhanced, i.e., the O contents lowered), and its amorphousness decreases.…”

“…Presence at the working atmosphere of the high oxygen content according to [16] leads to fast formation of oxides and, therefore, promotes formation of a tantalic layer in a beta state, whereas in [15], oxygen environment did not prevent the formation of alpha tantalum. At a deposition on silicon and glass substrates in [13,16,17], 0.5-0.7 Pa sputtering pressure led to α-Ta formation and smaller or bigger pressure-β-Ta, but in [15] already at 0.28 Pa, α phase was formed.…”

“…Development of the layered composite materials allowing to effectively combine desirable operational characteristics of the modified surface layers and the main material (substrate) at the present time is perspective in many areas of human activity: in optics (conducting, antireflecting, filtering, reflecting, and absorbing media), electronics (conductors, semiconductors, dielectrics), machine engineering, building and household (tribological, durable, wear-resistant, functional, protective, resistant to action of aggressive environment, decorative, and other coatings for structural and utility materials), medicine (biocompatible materials), etc. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17].…”

“…An effective and fairly common method for such surfaces formation is physical vapor deposition, including variations of magnetron sputtering, since at relatively small expenditure of time and resources, it allows to efficiently receive qualitative thin films of a diverse nature on substrate of virtually any nature and geometry and to control properties of the created materials [7][8][9][10][11][12][13][14][15][16][17]. The deposition method developed at the Baikov Institute of Metallurgy and Materials Science allows one to produce [coating-transition layer-substrate] nanocompositions from thermodynamically nonmiscible elements with good adhesion and resistance to external thermal and mechanical influences [18] and at the same time to avoid substrate overheating with bombarding electrons by keeping them near the sputtering target, which is of high importance for substrate materials with low melting points or phase structure that is sensitive to temperature changes [7].…”