Thin-film substrates

In 1988, Tanaka et al. first reported the use of ultrafine metal powder in protein analysis. Since then, many inorganic materials, including graphite particles, fine metal or metal oxide powder, silver thin-film substrates or particles,and silica gel, have been used in the MALDI-TOF analysis of low-mass molecules. 

With thin film substrates, it should be possible to locate the beam to an accuracy corresponding to the resolution of a transmission electron microscope (<0.5 nm). 

However, continuing development of spectroscopic sampling techniques in recent years has increasingly led to the use of non-metallic surfaces as thin-film substrates, and the structure of the adsorbed film on these surfaces is now being elucidated via spectroscopic techniques. Included in this group is the class of... 

The (de)hydrogenation process involves a change in volume, and, hence, the boundary conditions at the interface of the nanoparticles are expected to have an influence on the relative stability of the hydride with respect to the metal. For thin Aims it is known that 2 D clamping at the thin film/substrate interface can lead to very... 

Electron spin resonance has been reported on Yb and Nd impurities in EusGasOn (Hodges, 1975). The particular interest in this host is that the Eu ion has a singlet ground state and the lines are not broadened by the host. Microwave losses of GdsGasOn have been measured at 30 GHz, X-band, and 2 GHz by Adam et al. (1975). These measurements in this host are important in technological applications, as it is used as a nonreciprocal thin film substrate. 

Figure 25.2 Moore, L.A. CBC. See also Tietz, L.A., Carter, C.B, Lathrop, D.K., Russek, S.E., Buhrman, R.A., and Michael, J.R. (1989) Crystallography of YBa2Cu306+ c thin film-substrate interfaces, J. Mater. Res. 4,1072. Tietz, L.A., De Cooman, B.C., Carter, C.B., Lathrop, D.K., Russek,...

Wei L, Lakhtakia A, Roopnariane AP, Ritty TM. Human fibroblast attachment on fibrous parylene-C thin-film substrates. Mater Sci Eng C 2010 30(8) 1252-9. 

The concentration of proteins in blood plasma is 60 mg mL . In order to minimize any contribution to the signal by dissolved species [743], the ATR measurements are conducted in very dilute protein solutions ( 1 mg mL ). However, this is not the case with coated ATR, where the thickness of the thin-film substrate controls the penetration depth (see Section 4.1.3 for more detail). For example, at a solution concentration of 60 mg mL and under the optical conditions of 45° Ge MIRE coated with a 0.4-p,m-thick polymer coating, the contribution of the bulk solution was estimated to be 0.47% of the total spectra [769]. When it is necessary to follow adsorption at higher protein concentrations, special cells and measurement protocols based on internal standards are used for correcting for the bulk protein signal, which are discussed in detail by Jakobsen and Strand [743],... 

Kyocera has been conducting research and development on AIN and LTCC for more than 10 years, and has produced many kinds of AlN and LTCC products, such as Cer-Quad and multilayer packages, in addition to thin film substrates. Now, we have developed three materials for packages. The first is a novel AlN material (AN75W) that can co-fired at low temperature to reduce cost. The second is a novel LTCC that has a high thermal coefficient of expansion close to that for FR-4. The third is also a novel LTCC that has low permittivity... 

It is claimed to be able to measure thicknesses with an accuracy of about 0.3 A, approximately the thickness of an atomic layer. Because the method relies on polarized fight, ellipsometry is a nondestructive technique, which makes it suitable for in situ measurements in some cases. One disadvantage is that the substrate must be reflective, so gold or sUicon wafer is often used. However, a major disadvantage with the technique is interpretinging the data, which is not trivial models of the air—thin film-substrate must be used. The dielectric and optical properties of the thin film must be known accurately to calculate the thickness of the film, and even then the modelling usually assumes a homogeneous layer which may not always be justified. 

Nevertheless, preparation of the multilayer substrate surface is more complex and is usually carried out by the users instead of manufacturers of ceramic substrates. Simply applying a polymer layer onto the as-fired ceramic surface cannot lead to successful thin-film layers. The solvent trapped in microporosities in the conductor for vias and/or at the interface between conductor and ceramics may outgas during the reflow soldering when populating components on the finished thin-film substrate, resulting in poor adhesion of thin-film metal and dielectric at the position of vias. 

Brown, R., Thin film substrates. Handbook of Thin Film Technology, Maissel, L. and Glang, R., Eds., McGraw-Hill, New York, 1971. 

The effect of substrate thickness upon the short circuit current of p-n junction cells under AM4 is shown in figure 13. In practice the extent to which the thickness of single crystal solar cells may be reduced is normally limited by the fragility of the substrate - typically v 300 y thick. A similar limitation exists for Schottky Barrier cells, however, if thin film substrates are to be used it should be noted that the properties of the films will be widely different from the bulk material. This is particularly the case for a-silicon where absorption coefficients are more than 10 times greater and 5% efficient cells have been achieved using active regions 1, y thick. ... 

The various curvature measurement methods described in Section 2.3 provide convenient tools with which the film stress can be assessed by using the approaches outlined in Chapters 2 and 3 and Section 7.4. However, these approaches are often predicated on assumed microstructural conditions which may differ markedly from real behavior in some material systems. Microstructural evolution and competition between strain relaxation mechanisms can influence the evolution of substrate curvature during thermal excursions and the manner in which such effects are strongly affected by the geometry and material properties of the particular thin film-substrate system being considered. The following points are discussed in order in the remainder of the section, primarily in the context of polycrystalline metal Aims ... 

Masters, C. B. and Salamon, N. J. (1993), Geometrically nonlinear stress-deflection relations for thin film/substrate systems. International Journal of Engineering Science 31, 915-925. 

Usually, a ferroelectric thin film sample fabricated by the sol-gel method is coated on a substrate, which is much thicker than the film. The piezoelectric constant, 433, of the thin film sample can be measured by the static (or quasi-static) method and the electromechanical coupling factor 33 can be calculated from the known dielectric constant and the elastic coefficients 3. It is hard to measure a thin film/substrate system by a dynamic method, e.g., the transportation line method, because the vibrator is a thin film/substrate system and the major vibration is caused by the substrate, not by the film. 

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. 

Knowledge of particle-beam-induced chemical structural changes can be of key importance in the applications of the various thin-film-substrate systems, since it is central to either of the preparation-structure-property or the preparation-structure-performance type relationships. 

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