Vacuum thermal evaporation technique

Morales-Saavedra, O.G., Sanchez-Vergara, M.E., Ortiz-Rebollo. A., and Ortega- Martinez, R. 2007. Electrical and optical properties of Jager-nickel (Il)-based molecular-material thin films prepared by the vacuum thermal evaporation technique. Journal of Physics and Chemistry of Solids 68, 1571-1582. 

Although several methods may be used to fabricate the organic layers in OLEDs, such as thermal evaporation, Langmuir-Blodget deposition or spin coating from solutions, RE + /3-diketonates usually are deposited by thermal evaporation techniques, under high vacuum ca 10 Pa) thus, volatility and thermal stability of the diketonates are required. ... 

Techniques for thin-lilm deposition include vacuum thermal evaporation (Morales-Saavedra et al., 2007) and organized assembly. 

The separating layer optical thicknesses were fixed (Fig. 3) about or AqU, where corresponds to the plasmon absorption maximum of a metallic nanoparticle monolayer in the KCl environment. These multilayer structures were fabricated by the thermal evaporation technique followed by deposition of metal and dielectric materials without breaking the vacuum between the evaporation steps. The structures grown by this technique are realized as a sequence of Ag island films separated by KCl intermediate layers of a subwavelength thickness. These data... 

A number of processes are being used for producing nanomaterials for bulk production. The most common techniques used for synthesizing nanostructure materials include inert gas condensation, mechanical alloying, thermal spraying, electrodeposition, jet vapor deposition, vacuum thermal evaporation, and controlled chanical precipitation. 

In another context, the electrical properties of thin films obtained by different procedures, for example, thermal evaporation in vacuum, have been investigated in much detail. However, the films deposited by the LB technique have only recently been used in electrical applications. Thickness in LB films can be varied from only one monomolecular layer (ca. 25A = 25 10 10m), while this is not possible by evaporation procedures. 

Breakdown conduction in thin films, the major subject of investigation, has been based on the films prepared by thermal evaporation under vacuum or similar techniques. It was realized that LB films have remained less known among the investigators of this field. Their various interesting physical properties have been investigated in the current literature. 

Transmission Electron Microscopy (TEM) has been used to characterize aluminum thin films thermally evaporated (vacuum around 10 4 Torr) on Polyethyleneterephtalate (Mylar) and to correlate the crystallographic structure of the system Al/Mylar and the adhesion of the aluminum films. The adhesion of these films has been measured by a Peel test technique. For the polymer, an amorphous layer (t=12 nm) followed by a crystalline film have been observed on a Corona treated film and the opposite configuration has been found on a bi-axially stretched film. Some spherical precipitation ana interdiffusion zones have also be observed in the Mylar for the films which have the lower coefficient of adhesion (100 g/inch). The main conclusion is the augmentation of the adhesion of the aluminum film as the size of the grains decreases and/or as the microroughness of the Al/Mylar interface increases. 

Most devices based on Pc are fabricated by vacuum deposition, i.e. thermal evaporation. However, recent solution-based Langmuir-Blodgett (LB) techniques have also been used. LB-films of 25h-251 gave poor (10 cm V s for 25j) to moderate (1.7 x 10 cm V s for 251) mobilities (Figure 3.1.9).[162-164] More recently, high mobilities of 0.24-0.60 cm V s have been observed for LB films of amphiphilic tris(phthalocyaninato) rare earth triple-decker complexes, 25m-25o.[165] OFET characteristics have also been reported for porphyrin derivatives, 25p-q with mobilities of 2.2 x 10 cm V s and 0.012 cm V s, respec-tively.[166-168] LB-prepared thin films of Cyclo[8]pyrrole (25r), an extended porphyrin-like molecule, also exhibited a high mobility of 0.68 cm V s, but with a low on/off ratio.[169]... 

In thermal evaporation, solid materials are first vaporized by heating at sufficiently high temperature in vacuum, and then a thin film is formed on a cooler substrate by condensation of the vapor. This technique can be used for the deposition of thin layers made of such metals as Ag or Pt that are active in gas separation. 

Figure 1.1 PVD Processing Techniques (a) Vacuum Evaporation, (b) and (c) Sputter Deposition in a Plasma Environment, (d) Sputter Deposition in a Vacuum, (e) Ion Plating in a Plasma Environment with a Thermal Evaporation Source, (f) Ion Plating with a Sputtering Source,...

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