Fishing – trapping – and vermin destroying
Patent
1989-04-05
1992-01-07
James, Andrew J.
Fishing, trapping, and vermin destroying
357 71, 437175, 437176, 437177, 437184, 437904, H01L 2948, H01L 2956, H01L 2964, H01L 2348
Patent
active
050795961
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a Schottky diode having a substrate layer made from gallium arsenide. A thin gallium arsenide layer is located on the side of the substrate facing away from the metallized connecting contact surface. Another layer is applied on this thin gallium arsenide layer to form a Schottky contact, which is further provided with a second metallized connecting contact surface.
Diodes of the Schottky type are known in the art and include a layer made from indium tin oxide (InSnO.sub.2) as the layer forming the Schottky contact. The indium tin oxide layer, which is not monocrystalline, is applied, for instance, after the epitaxial application of the thin gallium arsenide layer in a molecular beam epitaxy system using a separate apparatus, for instance, by sputtering or vaporization. A disadvantage with this is that changing the equipment exposes the still unfinished components to damage. Further, the equipment change makes the manufacturing process more time consuming and thus more expensive.
Based on this prior art, the problem underlying the invention is to provide a Schottky diode of the aforementioned type which can be manufactured in a simple manner by using a high yield system and process, and which is distinguished from the prior art by high efficiency.
SUMMARY OF THE INVENTION
This problem is inventionally solved in that the thin layer forming the Schottky contact is a monocrystalline layer from a monopnictide. Preferably, erbium arsenide or ytterbium arsenide is used as the monopnictide, which is applied using the same molecular beam epitaxy system as for the thin gallium arsenide layer.
Since the layer made from erbium arsenide or ytterbium arsenide is monocrystalline and not polycrystalline, more uniform conditions of conductivity and a more favorable reflective performance of the Schottky diode for light are obtained when using it as a photodetector. The more uniform conductivity results in a better efficiency. Since the inventional Schottky diode can be manufactured in a system without interruption of the manufacturing process, there is a high yield obtained with no risk of contamination in transporting the semifinished components from one system to another for subsequent process steps.
Suitable designs and advancements of the invention are set forth in the dependent claims.
BRIEF DESCRIPTION OF THE DRAWING
An embodiment of the invention will be more fully explained hereafter with the aid of the drawing, which comprises one FIGURE.
The drawing depicts a schematic perspective view of a Schottky diode that can be used as photodetector and whose thickness, for illustration purposes, is shown exaggerated in size as compared to its other dimensions .
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
On the Schottky diode illustrate in the drawing, the first connecting electrode is designed as a large-area metal electrode 1. The second connecting electrode, which when used as a photodetector is located on the side of the light incidence, is fashioned as U-shaped metal contact strip 2. The large-area metal electrode 1 is connected in customary fashion with a contact wire 3, and the metal contact strip 2 is connected with a contact wire 4.
The large-area metal electrode 1 is located on the underside of a substrate 5, which is made from electrically conductive gallium arsenide doped with silicon. Grown on the substrate 5 from gallium arsenide, epitaxially, is a thin monocrystalline gallium arsenide layer 6 of low electrical conductivity. As with substrate 5, monocrystalline gallium arsenide layer 6 also contains silicon impurity.
The next layer in the laminate sequence of the Schottky diode consists of a thin layer 7 made from erbium arsenide or ytterbium arsenide that is grown in place of a monocrystalline. For light with a wavelength of less than 1 um, this layer has the property of being entirely transparent, so that a transparent Schottky contact is formed. Resulting from the monocrystalline structure is a uniform conductivity and a favorable reflecti
REFERENCES:
patent: 4394673 (1983-07-01), Thompson et al.
patent: 4803539 (1989-02-01), Psaras et al.
patent: 4847675 (1989-07-01), Eng
Waldrop, "Rare Earth Metal Schottky-Barrier Contact to GaAs", May 1985, pp. 864-866.
Journal of the Physical Society of Japan, Band 42, Nr. 2, Feb. 1977, Tokyo, JP, A. Hasegawa et al., "Energy Band Structures of Gd-Pnictides", pp. 492-498.
J. Phys. C: Solid St. Phys., Band 13, 1980, The Institute of Physics, (London, GB), A. Hasegawa, "Electronic Structure of La Monopnictides", pp. 6147-6156.
Applied Physics Letters, Band 46, Nr. 9, 1 May 1985, American Institute of Physics, (Woodbury, N.Y., US), J. R. Waldrop: "Rare-Earth Metal Schottky-Barrier Contacts to GaAs", pp. 864-866.
Smith Robin
Wennekers Peter
James Andrew J.
Kim Daniel
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