Metal layers on glass

THE FIRING ON OF METAL LAYERS ON GLASS Platinum, Gold and Palladium... 

In a case of 30keV-EB drawing of magiKtic and metal layers on glass substrate, the minimum dot pitch was near 25 nm. Main cause may be charge-up of the glass. 

Figure 9.7 Three configurations for sandwich-type thin-layer cells. (A) Minigrid suspended between two spacers. (B) Twin-electrode cell using metal films on glass. (C) Single-electrode cell, barrier plate and electrode plate, s, Sample solution.

The materials (metals and conjugated polymers) that are used in LED applications were introduced in the previous chapter. The polymer is a semiconductor with a band gap of 2-3 eV. The most commonly used polymers in LEDs today are derivatives of poly(p-phenylene-vinylene) (PPV), poly(p-phenylene) (PPP), and polythiophene (PT). These polymers are soluble and therefore relatively easy to process. The most common LED device layout is a three layer component consisting of a metallic contact, typically indium tin oxide (ITO), on a glass substrate, a polymer film r- 1000 A thick), and an evaporated metal contact4. Electric contact to an external voltage supply is made with the two metallic layers on either side of the polymer. 

SF6 glass prisms were thoroughly cleaned, rinsed with organic solvents, treated in a plasma cleaner and, subsequently, heated in a vacuum chamber to a temperature of approx. 100 °C. A 50 nm gold film was deposited. During deposition the vacuum chamber was evacuated to 10-3 Pa. The thickness of the metal layer on the prism was con-... 

A heated sample holder, based on the design of Frei and Frodyma (14), which could be used for studying small samples, was recently described by Wendlandt (15). The sample is placed as a thin layer on glass fiber cloth which is secured to the heated aluminum metal block by a metal clamp and a cover glass. Dimensions of the aluminum block are 4.0 by 5.0 cm. The block is heated by a circular heater element contained within, the holder. Electrical connections to the heater and to the thermocouple are made by means of the terminal strip mounted at the top of the assembly. Both the aluminum block and the terminal strip are mounted on a 5.0 by 5.0-cm transite block. 

Disposable microprizm and photodiode were placed on a rotary table (10 arc sec resolution). Before depositing metal layers, the glass surface of the microprizm was treated with a chromium mkture, rinsed in bi-distilled water and then dried in a dust-fiee airflow. Au layer (thickness 45 run) was deposited onto the quartz surface of microprizm in special vacuum sets equipped with oil pumps and nitrogen traps (pressure 10 Pa). Before deposition, the mikroprizm surface was ion-bombarded in a vacuum (pressure 1 Pa). In order to increase the chip stability in the aqueous environment, Au film was modified by covalent binding of the thiol contained 12-carbohydrate spacer. 

Many sputtered metals do not adhere particularly well to typical device substrate materials such as silicon, glass, and polymers. For example, noble metals such as Au can only rely on van der Waals forces for adhesion, and these forces are relatively weak. Metals such as Cr, Al, and Ti readily form a suboxide interface layer on glass and so they are often used as adhesion layers. 

Since doped polyacetylenes were shown to possess metallic conductivity, this class of organic polymers has been studied intensively. Regardless of the catalyst system used, it is an inherent disadvantage of the standard type of polymerization that ultimately a washing process is required to remove the catalyst or its residues from the desired polymer preparation. A method was therefore developed that avoids this pitfall and provides polyene films that form a solid layer on glass surfaces, ceramic plates, tubes, etc. 

The second technique is that of transmission spectroscopy through transparent electrodes. The principle of this technique is the same as that of absorbtion spectroscopy whereby if an absorbing substance is present in the diffusion layer near a transparent electrode its spectrum could be recorded in the usual way. The problem with this technique is obviously the need for a transparent electrode. Germanium and doped tin oxide can be used, as can a very thin layer of metal deposited on glass or silica plates. The thin layer can be reduced to a grid which will give conductance to the surface of the plate without making it too opaque. 

As a second example, results from a TOP ERDA measurement for a multi-element sample are shown in Fig. 3.65 [3.171]. The sample consists of different metal-metal oxide layers on a boron silicate glass. The projectiles are 120-MeV Kr ions. It can be seen that many different recoil ions can be separated from the most intense line, produced by the scattered projectiles. Figure 3.66 shows the energy spectra for O and Al recoils calculated from the measured TOF spectra, together with simulated spectra using the SIMNRA code. The concentration and thickness of the O and Al layers are obtained from the simulations. 

If the rf source is applied to the analysis of conducting bulk samples its figures of merit are very similar to those of the dc source [4.208]. This is also shown by comparative depth-profile analyses of commercial coatings an steel [4.209, 4.210]. The capability of the rf source is, however, unsurpassed in the analysis of poorly or nonconducting materials, e.g. anodic alumina films [4.211], chemical vapor deposition (CVD)-coated tool steels [4.212], composite materials such as ceramic coated steel [4.213], coated glass surfaces [4.214], and polymer coatings [4.209, 4.215, 4.216]. These coatings are used for automotive body parts and consist of a number of distinct polymer layers on a metallic substrate. The total thickness of the paint layers is typically more than 100 pm. An example of a quantitative depth profile on prepainted metal-coated steel is shown as in Fig. 4.39. 

Conventionally RAIRS has been used for both qualitative and quantitative characterization of adsorbed molecules or films on mirror-like (metallic) substrates [4.265]. In the last decade the applicability of RAIRS to the quantitative analysis of adsorbates on non-metallic surfaces (e.g. semiconductors, glasses [4.267], and water [4.273]) has also been proven. The classical three-phase model for a thin isotropic adsorbate layer on a metallic surface was developed by Greenler [4.265, 4.272]. Calculations for the model have been extended to include description of anisotropic layers on dielectric substrates [4.274-4.276]. 

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