Thin films complex structured

Constructing an optical model. In the data analysis procedure in ellipsometry, an optical model corresponding to the investigated sample structures must be constructed firstly. An optical model is represented by the complex refractive index and layer thickness of each layer, normally, it consists of an air/thin film/ substrate structure. It should be decided if any layer is anisotropac at this stage, and whether or not interface layers are to be modeled as a single effective medium approximation, or is a more complicated graded interface to be used for the sample. 

Sputtered Neutral Mass Spectrometry (SNMS) is the mass spectrometric analysis of sputtered atoms ejected from a solid surface by energetic ion bombardment. The sputtered atoms are ionized for mass spectrometric analysis by a mechanism separate from the sputtering atomization. As such, SNMS is complementary to Secondary Ion Mass Spectrometry (SIMS), which is the mass spectrometric analysis of sputtered ions, as distinct from sputtered atoms. The forte of SNMS analysis, compared to SIMS, is the accurate measurement of concentration depth profiles through chemically complex thin-film structures, including interfaces, with excellent depth resolution and to trace concentration levels. Genetically both SALI and GDMS are specific examples of SNMS. In this article we concentrate on post ionization only by electron impact. 

Complete elemental analysis of complex thin-film structures to several pm depth, with excellent depth resolution... 

If the secondary ion component is indeed negligible, the measured SNMS ion currents will depend only on the ionizing mode, on the atomic properties of the sputtered atoms, and on the composition of the sputtered sample. Matrix characteristics will have no effect on the relative ion currents. SNMS analysis also provides essentially complete coverage, with almost all elements measured with equal facility. All elements in a chemically complex sample or thin-film structure will be measured, with no incompleteness due to insensitivity to an important constituent element. Properly implemented SNMS promises to be a near-universal analytical method for solids analysis. 

The SIMS analytical ion signal of a specific element or isotope also can be enhanced by selective ionization of particular atoms, and the detection limit for that element thereby improved. This mode of SNMS is important to specific applications, but it lacks the generality inherent in nonselective SNMS methods. The focus of this article will be on the methods for obtaining complete, accurate, and matrix-independent compositions of chemically complex thin-film structures and materials. 

In summary, the forte of SNMS is the measurement of accurate compositional depth profiles with high depth resolution through chemically complex thin-film structures. Current examples of systems amenable to SNMS are complex III-IV laser diode structures, semiconductor device metallizations, and magnetic read-write devices, as well as storage media. 

Epitaxy. There is often a sharp orientation relationship between a singlecrystal substrate and a thin-film deposit, depending on the crystal structures and lattice parameters of the two substances. When such a relationship exists, the deposit is said to be in epitaxy with the substrate. The simplest relationship is parallel orientation, and this is common in semiconductor heterostructures, but more complex relationships are often encountered. 

The case of isotactic polypropylene (iPP) presents some differences with respect to those just discussed. While both sPP and PET adopt in their mesophases disordered, extended, essentially non-helical conformations, iPP is characterized by a unique, relatively well ordered, stable chain structure with three-fold helical symmetry [18,19,36]. More accurately we can state that an iPP chain segment can exist in the mesophase either as a left handed or as the enantiomeric right-handed three-fold helix. The two are isoener-getic and will be able to interconvert only through a rather complex, cooperative process. From a morphological point of view Geil has reported that thin films of mesomorphic iPP quenched from the melt to 0 °C consist of... 

Unfortunately, TiN is difficult to prepare in bulk form without porosity. Therefore, measured values of its properties show considerable scatter. In particular, consistent values for its hardness from one investigator to another are not available. They range from 1600 to 4000kg/mm2. For practical applications, TiN is used in the form of thin films. These are consistent in their hardnesses, but their complex structures make them difficult to interpret in terms of simpler quantities. 

Bulk NLO studies on luminescent /uc- ReI(CO)3(a-diimine) + complexes by Yam and co-workers note SHG from surfactant derivatives such as (54) and (55) deposited in Langmuir-Blodgett (LB) thin films.110-112 For example, the 532 nm SHG from LB films of the stilbazole derivative (55) is ca. 50% more intense than that from films of the structurally related purely organic salt traiw-.lV-methyl-4-[2-(4-octadecyloxyphenyl)ethenyl]pyridinium iodide.112... 

Again, we are reminded that Nature provides the ultimate model for emulation in the use of cooperative interactions of an enormous number of small structural components through many weak, reversible attractions and repulsions to produce such complex microstructures as proteins, enzymes, viruses, and cells with virtually perfect fidelity (Whitesides, 1991). One important strategy for producing ultra-thin films of promise for microelectronics... 

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