Thin film materials applications

Microfabrication is a series of thin film material application (deposition) and removal (etch) steps, that are used to create mechanical or electronic structures in and/or on a substrate. Photolithography is the method... 

Hollingsworth, J. A. Buhro, W. E. Hepp, A. F. Jenkins, P. P. Stan, M. A. 1998. Spray chemical vapor deposition of CuInS2 thin films for application in solar cell devices. Chemical Aspects of Electronic Ceramics Processing, edited by Kumta, P. N. et al., MRS Symp. Proc., Vol. 495, Materials Research Society, Pittsburgh, PA, pp. 171-176. 

In this artide, we review the new field of combinatorial materials science. We describe in detail our particular materials exploration approach that we call the continuous compositional spread (CCS) approach. This CCS approach allows the synthesis and characterization of a major fraction of a ternary or pseudo-ternary phase spread in about 24 hours. We compare the CCS approach with other schemes for rapid materials investigations. We also provide an example of the successful application of the CCS approach in the discovery of a new high dielectric constant thin-film material, an amorphous zirconium tin titanate, aZTT. New combinatorial approaches to materials research can allow us to do studies that would not have been possible using conventional techniques. 

The research plan is organized around a set of well-defined model systems and a limited number of detailed experiments. The experiments are designed to progress over a five-year period from fundamental studies on model systems to development of thin film materials with potential practical applications. Together they will form a coherent bond of film growth using LCI with a variety of molecular building and LC solvents. The expected outcomes of this work will be... 

Coercivity of Thin-Film Media. The coercivity in a magnetic material is an important parameter for applications but it is difficult to understand its physical background. It can be varied from nearly zero to more than 2000 kA/m in 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 influenced by the microstructural properties of the layer such as crystal size and shape, composition, and texture. These properties are diiecdy related to the preparation conditions. Material choice and chemical inhomogeneties are responsible for the M of a material and this is also an influencing parameter of the final FF, 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 in the different thin-film materials in detail. 

The results illustrated above show that the CFT method is suitable for making chemical-sensor measurements using both bulk polymers and, in particular, thin film materials that are intrinsically weak conductors. Therefore, the CFT looks premising for such materials as poly(phenylacetylene) derivatives 24., for which carefully shielded electrometer measurements have been required in the past because of current levels at the threshold of detectability. Furthermore, the fact that the CFT always makes AC measurements reduces the problem of DC polarization of electrodes. In addition, the CFT approach should be suitable for other "chemiresistor" applications, such as the metal-substituted phthalocyanines proposed by Jarvis et. al. 2 and for Langmuir—Blodgett films 26. which, because they are so thin, may prove impossible to use in parallel-plate form, but which can be routinely used with the high-sensitivity interdigi-tated-electrode approach provided by the CFT. 

Polyoxometalates are important catalysts but they are also finding application in optical, electrical, and magnetic devices. Mixed-metal polyoxometalates with vanadium(V) in the polyoxoanion core confers enhanced properties to such structures, principally in their ability to form essentially infinite networks that can be utilized as coatings or as other thin film materials. Additionally, these materials have tunable electromagnetic and photochromic properties. In combination with organic polymers, so-called hybrid polymers, special electrochemical properties are conferred, making possible such electrical storage devices such as capacitors and batteries that utilize the redox properties of the polyoxometalate [7],... 

Configurational stability (or persistence) is one of the important properties of a chiral material. The definition of the lower limit for the free energy barrier for racemization may depend on the specific application. For optoelectronic applications, accelerated aging tests may provide very approximate guidelines [114]. For the purpose of estimating the free energy barrier for racemization, we will assume that the less than 1 % conversion of the major enantiomer to the minor enantiomer in such aging tests is tolerable, i.e. Aa / a < 0.02, where a (in units °mm 1) denotes rotatory power of thin-film material. With these assumptions,... 

In this chapter, we explore the current and potential future applications of AW devices for materials characterization and process monitoring. Because of the limited mass of material that can be applied to the AW device surface, the majority of these applications deal with the chemical and physical characterization of thin-film properties. This thin film focus should not be thought of as a limitation of AW devices, but rather as a useful capability — the direct measurement of properties of materials in thin-film form. Since material properties can depend on the physical form (e.g., film, bulk) of the material (see Section 4.3.1.3), AW devices are uniquely suited to directly characterize thin-film materials. These considerations also indicate that even though it is possible to use AW thin-film data to predict bulk material properties, such extrapolations should be performed with care. 

In conclusion, the results presented in this chapter demonstrate the extreme versatility of AW devices for the characterization of materials. The inherent sensitivity of AW properties to the mechanical and electrical properties of thin films can be used to advantage to directly monitor a wide variety of film properties. Since the properties and behavior of thin-film materials can be very different from those of similar bulk materials, this ability to directly measure thin film properties can be a significant advantage in materials research and development. The ability to use thin films instead of bulk samples has the added advantage that the time required to perform an evaluation of dynamic processes such as diffusion and corrosion can be greatly decreased. The number of applications of AW devices to thin-film characterization continues to increase, and is limited only by the ingenuity of AW device researchers and developers. 

Lin M-T, El-Deiry P, Chromik RR, Barbosa N, Brown WL, Delph TJ, Vinci RP. Temperature-dependent microtensile testing of thin film materials for application to microelectromechanical system. Microsyst Technol 2006 12(10-11) p 1045-1051. 

---