Film materials properties

R. Lucklum, P. Hauptmaim and R.W. Cemosek, Thin Film Material Properties Analysis with Quartz Crystal Resonators, IEEE Intemational Frequency Control Symposium, (2001) 542-50. 

Coercivity of Thin-Film Media. The coercivity ia a magnetic material is an important parameter for appHcations but it is difficult to understand its physical background. It can be varied from nearly zero to more than 2000 kA/m ia a variety of materials. For thin-film recording media, values of more than 250 kA / m have been reported. First of all the coercivity is an extrinsic parameter and is strongly iafluenced by the microstmctural properties of the layer such as crystal size and shape, composition, and texture. These properties are directly related to the preparation conditions. Material choice and chemical inborn ogeneties are responsible for the Af of a material and this is also an influencing parameter of the final In crystalline material, the crystalline anisotropy field plays an important role. It is difficult to discriminate between all these parameters and to understand the coercivity origin ia the different thin-film materials ia detail. 

T and are the glass-transition temperatures in K of the homopolymers and are the weight fractions of the comonomers (49). Because the glass-transition temperature is directly related to many other material properties, changes in T by copolymerization cause changes in other properties too. Polymer properties that depend on the glass-transition temperature include physical state, rate of thermal expansion, thermal properties, torsional modulus, refractive index, dissipation factor, brittle impact resistance, flow and heat distortion properties, and minimum film-forming temperature of polymer latex... 

Strained set of lattice parameters and calculating the stress from the peak shifts, taking into account the angle of the detected sets of planes relative to the surface (see discussion above). If the assumed unstrained lattice parameters are incorrect not all peaks will give the same values. It should be borne in mind that, because of stoichiometry or impurity effects, modified surface films often have unstrained lattice parameters that are different from the same materials in the bulk form. In addition, thin film mechanical properties (Young s modulus and Poisson ratio) can differ from those of bulk materials. Where pronounced texture and stress are present simultaneously analysis can be particularly difficult. 

These materials can only be cured at relatively high temperatures (typically, 130-300°C). Therefore, the process is normally carried out at works. With the use of special reactors, it can be accomplished on-site but the operation is difficult. In all cases, the application is critical, and variations in temperature and cure time will result in different film-forming properties. The application should always be left to specialists. 

Extender an inorganic material in powder form which has a low refractive index and consequently little obliterating power, but is used as a constituent of paints to adjust the properties of the paint, notably its working and film-forming properties and to avoid settlement on storage. 

It practice it is usually difficult to establish the reasons for failure as a number of factors may be simultaneously responsible, such as (n) application of the protective to dirty surfaces, (b) carelessness in application, (c) inherent inadequacy of the material, (rf) exposure to unreasonably severe conditions, (e) inevitable difficulties in application. Point (c) includes inadequacy not only in protective properties but, in the case of the hard-film materials, in certain physical properties, e.g. the film may become brittle and flake when handled, may remain too sticky and become contaminated with dirt or adhere to the... 

As a result of the deterioration of film properties with increasing power levels, to obtain device quality material the use of low power is required, albeit with a concomitant low deposition rate. Increasing the deposition rate without altering the device quality material properties is a large research challenge. 

It has been found that various material properties are thickness-dependent. Raman experiments show a dependence on the type of substrate (glass, c-Si, stainless steel, ITO on glass) and on the thickness (up to 1 /nm) of the films [392,393]. Recent transmission electron microscopy (TEM) results also show this [394]. This is in contrast to other results, where these effects are negligible for thicknesses larger than 10 nm [395, 396], as is also confirmed by ellipsometry [397] and IR absorption [398] studies. 

FIG. 43. Measured and simulated thickness profiles on the substrate behind the slit for a film deposited under discharge conditions that typically yield good material properties (a) along the length of the slit, (b) across the slit. The vertical dashed-dotted lines indicate the boundaries of the apertures. The dotted lines represent the measured profiles, the solid lines the simulated profiles. The dashed lines are the simulated deposition profiles of the radicals. (From E. A. G. Hamers. Ph.D. Thesis, Universiteit Utrecht, Utrecht, the Netherlands, 1998. with permission.)... 

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