DE9206100U1 - Device for changing the static electrical potential of a surface made of insulating material - Google Patents

Description

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DEVICE FOR CHANGING THE STATIC ELECTRICAL POTENTIAL OF A SURFACE MADE OF INSULATING MATERIAL

The invention relates to a device for changing the static electrical potential of a surface made of insulating material by means of an electrode whose active surface faces the surface made of insulating material and has a fine structure whose structural elements are starting points of a corona charge.

A device of this type is known from EP 0295431 Bl, in which the active elements are the tips of non-metallic, electrically conductive fibers, which are arranged individually in bunches lengthwise next to one another, namely at around 100,000 fiber ends per square centimeter. In this way, a fine structure is achieved in the active surface, which promotes the formation of a corona discharge emanating from the entire active surface. Such a corona discharge is favorable for a controlled change in potential.

In order to achieve the desired effect, it is important that individual active elements are equally well positioned in terms of potential so that the corona discharge is evenly distributed and not concentrated in favorably located local areas.

The object of the invention is to create a device of the type mentioned at the outset with the highest possible fine structure in the active surface, taking into account the previously mentioned functional conditions, which can be produced as easily and reproducibly as possible.

The invention solves this problem by using fullerene molecules as structural elements.

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Fullerenes are so-called cage molecules made of spherically arranged C atoms, preferably with the chemical formula C _2n , where η = 30, i.e. the chemical formula CgQ, has proven particularly useful.

According to the invention, individual fullerene molecules take over the function of the fiber ends in the known device. Fullerene molecules can be arranged in the desired structure, more simply than fiber tufts, and the conductivity can also be controlled in a very differentiated way by making the fullerenes conductive in the desired way through doping.

For a doped fullerene molecule, the molecular formula is X _r C _2n

with X=H, Li, Na, K, Rb, Cs and/or Fr with r = 0, 1, 2, ..., preferably 1 with η = 16, 17, 18, ..., preferably 30.

The foreign atoms X are added to the fullerene by doping, incorporation, addition and/or admixture. A doped fullerene with the molecular formula KoCgQ is particularly preferred.

The fullerenes can be applied in different ways, for example with the help of a laser. Electrolytic application is advantageous because it is easy to handle and makes the application of the cage molecules easy to control, for example using electric fields.

It is also advantageous and easy to control very precisely if the fullerenes that form the active surface are placed on the crystal surfaces of a semiconductor, preferably gallium arsenide, gallium-aluminium arsenide, aluminum-gallium arsenide, indium phosphide or indium gallium arsenide.

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The semiconductor can then simultaneously serve as a power supply to the fullerenes.

The fullerenes forming the active surface are preferably applied in the form of a monomolecular layer with a crystal structure. This results in a uniform pattern of electrically active elements over the entire active surface.

The fullerenes of a monomolecular layer can be arranged in a single plane, they can be molecules of the same size, they can be molecules with the same doping and/or these molecules can be arranged spherically identically in the layer with regard to their doping.

The monomolecular layer can also be designed differently with regard to the criteria listed, but while maintaining a grid that requires an even distribution of the active elements. A corresponding design is characterized by the fact that the fullerenes forming the active surface are divided into several groups, that the fullerenes of the individual groups are mixed and arranged to form a grid, that the fullerenes of one group are the same size, equally doped and spherically oriented with regard to their doping, and that the fullerenes of different groups differ from one another in terms of size, doping, spherical arrangement and/or their arrangement in different planes.

The invention will now be explained in more detail with reference to the accompanying drawing.

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In the drawing shows:

Figure 1 shows a device according to the invention broken away in perspective, Figures 2, 3 and 4 are a raster image and Figure 5 is a table.

In Figure 1, 1 denotes a metallically conductive support body which is coated with a semiconductive, crystalline gallium arsenide layer 2. A monomolecular layer 3 made of fullerene molecules 4 is grown or electrolytically applied onto the layer 2, the molecular arrangement of which is based on a crystal structure, in this case a regular column and row pattern, due to the crystal structure of the gallium arsenide layer 2.

The individual fullerene molecules are made conductive by doping and form, each of them, the starting point of a corona discharge, which is caused by a potential difference between the layer 3 and the opposite surface 6 of an element 7 made of insulating material, the static electrical potential of which is to be changed by the corona discharge.

According to some modifications, the fullerene molecules forming the active surface consist of two or three groups, of which those of the first group are designated A according to Figures 2, 3 and 4, those of the second group are designated B and those of the third group are designated C. The molecules are arranged in a grid as indicated by the arrangement of the letters in Figures 2 to 4. The molecules of the individual groups can differ, as will now be explained using Figure 5.

In line I of Figure 5 there are three equal and

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Equally doped fullerene molecules are shown, which, however, differ in their spherical arrangement with regard to their doping, which is indicated by a black dot.

Row II shows three identical fullerene molecules that are doped differently: one molecule with one doping element, the next with two doping elements, and the last with three doping elements.

Row III shows fullerene molecules that differ in size.

In row IV, fullerene molecules are shown that differ in the type of doping used, which is graphically expressed by the doping being represented once by a circle, once by a triangle and once by a square.

In row V, identical fullerene molecules are shown, but arranged in different planes 10, 11, 12, where the two outer planes 10 and 12 are spaced apart by the order of the diameter of a fullerene molecule.

In row VI, the fullerene molecules are doped with the conductivity type &rgr;, &eegr; and &rgr;.

The first group, marked by the letter A, is assigned to those molecules in rows I to V that are in column A and so on for column B and column C. Rows I to VI, in conjunction with Figure 2, each define an embodiment for itself. The same applies to Figures 3 and 4. In the case of these resulting

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&khgr; 6 = 18 embodiments, the fullerenes always differ by only one criterion. Further embodiments are possible in which the molecules of the individual groups A, B and C differ by two, three or more of the criteria defined by rows I to V.

Further modifications are possible by using more than three groups. It is also possible to modify the grid in Figure 2 and assign a different number of members to the individual groups. The only important thing is that the active surface has a uniform grid throughout, so that the active elements are evenly distributed over the active surface. All fullerene molecules used in a monomolecular layer can then form active elements, but depending on the arrangement, only selected molecules in a monomolecular layer can also form active elements, for example only molecules A in the embodiments according to line V in Figure 3.

Claims (10)

- 1 - P 69 415 29.4.1992. CLAIMS 1. Device for changing the static electrical potential of a surface made of insulating material by means of an electrode whose active surface faces the surface made of insulating material and has a fine structure whose structural elements are starting points of a corona charge, characterized in that the structural elements (4, 5) are fullerene molecules. 2. Device according to claim 1, characterized in that fullerenes made conductive by doping are used. 3. Device according to one of the preceding claims, characterized in that the fullerenes are deposited electrolytically. 4. Device according to claim 1 or 2, characterized in that the fullerenes are grown on the crystal surfaces of a semiconductor, preferably gallium arsenide, gallium-aluminium arsenide, aluminium-gallium arsenide, indium phosphide or indium gallium arsenide. 5. Device according to one of the preceding claims, characterized in that the fullerenes forming the active surface are applied in the form of a monomolecular layer ( 3 ). 6. Device according to claim 5, characterized in that the monomolecular layer ( 3 ) is based on a crystal structure. - 2 - P 69 415 2-S.4.1992. 7. Device according to one of the preceding claims, characterized in that fullerenes of equal size are used for the active surface. 8. Device according to one of the preceding claims, characterized in that equally doped fullerenes are used for the active surface. 9. Device according to one of the preceding claims, characterized in that the fullerenes forming the active surface are arranged with the same spherical orientation with regard to their doping. 10. Device according to one of claims 1 to 8, characterized in that that the fullerenes forming the active surface are divided into several groups, that the fullerenes of the individual groups are mixed, arranged to form a grid, that the fullerenes of a group are of equal size, equally doped and arranged in the same spherical orientation with respect to their doping and that the fullerenes of different groups differ from each other in terms of size, doping, spherical arrangement and/or their arrangement in different planes. (Fig. 2-5)