Thin Films and Vapor Deposition

The U.S. electronics industry appears to be ahead of, or on a par with, Japanese industry in most areas of current techniques for the deposition and processing of thin films—chemical vapor deposition (CVD), MOCVD, and MBE. There are differences in some areas, thongh, that may be cracial to future technologies. For example, the Japanese effort in low-pressure microwave plasma research is impressive and surpasses the U.S. effort in some respects. The Japanese are ahead of their U.S. counterparts in the design and manufacture of deposition equipment as well. 

Epitaxially grown thin films of vapor-deposited organic compounds and defect structures in these films have been studied by electron diffraction and high-resolution imaging with TEM [23]. Here, epitaxial crystallization of polymers is briefly described. 

Tiitta M, Niinisto L (1997) Volatile metal beta-diketonates, ALE and CVD precursors for electrolimiinescent device thin films. Chemical Vapor Deposition 3(4), 167-182... 

The preceding treatment is, undoubtedly, an oversimplification. For example, many diatomic molecules dissociate upon adsorption (e.g., H2, SiH, GeH). Each atom from the dissociated molecule then occupies its own distinct surface site and this naturally changes the rate law expression. When these types of details are accounted for, the Langmuir-Hinshelwood mechanism has been very successful at explaining the growth rates of a number of thin-film chemical vapor deposition (CVD) processes. However, more important, our treatment served to illustrate how crystal growth from the vapor phase can be related to macroscopic observables namely, the partial pressures of the reacting species. 

S. A. Mlddlebrooks. Modelling and Control of Silicon, and Germanium Thin Film Chemical Vapor Deposition. PhD Dissertation, University of Wisconsin, Madison, Wisconsin, 2001. 

Adsorbates of molecules or ions from solution onto the electrode as a function of electrode potential or concentration in solution can be investigated. The electrode to be investigated is prepared as a thin film by vapor deposition onto a suitable insulating (monocrystalline, if desired) substrate. For simultaneous measurements of film resistance and electrode potential an electrode design as depicted in Fig. 7.30 provides an optimum compromise between current distribution and a minimum of interference between both measurements [258],... 

Tamada, M., Omichi, H., and Okui, N., Preparation of polyvinylcarbazole thin-film with vapor deposition polymerization, Thin Solid Films, 268, 18-21 (1995). 

Deposition of Thin Films. Laser photochemical deposition has been extensively studied, especially with respect to fabrication of microelectronic stmctures (see Integrated circuits). This procedure could be used in integrated circuit fabrication for the direct generation of patterns. Laser-aided chemical vapor deposition, which can be used to deposit layers of semiconductors, metals, and insulators, could define the circuit features. The deposits can have dimensions in the micrometer regime and they can be produced in specific patterns. Laser chemical vapor deposition can use either of two approaches. 

The substituted five-ring OPVs have been processed into poly crystal line thin films by vacuum deposition onto a substrate from the vapor phase. Optical absorption and photolumincscence of the films are significantly different from dilute solution spectra, which indicates that intermolecular interactions play an important role in the solid-state spectra. The molecular orientation and crystal domain size can be increased by thermal annealing of the films. This control of the microstruc-ture is essential for the use of such films in photonic devices. 

Fell, W. A., Wessels, B., Tonge, L., and Marks, T., Chemically Vapor Deposited Strontium Titanate Thin Films and Their Properties, Proc. 11th. Int. Conf. on CVD, (K. Spear and G. Cullens, eds.), pp. 148-154, Electrochem. Soc., Pennington, NJ 08534(1990)... 

Engelken RD, McCloud HE, Lee C, Slayton M, Ghoreishi H (1987) Low temperature chemical precipitation and vapor deposition of SnxS thin films. J Electrochem Soc 134 2696-2707... 

To date, most small molecule-based OLEDs are prepared by vapor deposition of the metal-organic light-emitting molecules. Such molecules must, therefore, be thermally stable, highly fluorescent (in the solid state), form thin films on vacuum deposition, and be capable of transporting electrons. These properties limit the number of metal coordination compounds that can be used in OLED fabrication. 

The photoelectrochemical behavior of a given photoanode is dependent on its method of synthesis. Various methods, some of which we now briefly consider, such as anodic oxidation, spray pyrolysis, reactive sputtering and vapor deposition are commonly employed to make polycrystalline thin films. 

A glass substrate carrying an ITO film having a thickness of 150 nm was spin coated with 70 nm of poly(3,4)ethylenedioxythiophene/polystyrenesulfonic acid thin film and then dried at 200°C for 10 minutes. A 50-nm coating of a selected experimental agent was sprayed onto the initial film and dried. Lithium fluoride, calcium, and aluminum were then vapor-deposited at 0.4 nm, of 5 and 180nm, respectively. 

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