Temic Telefunken Microelectronic Gmbh

Telefunken Electronic Gmbh

Vishay Semiconductor Gmbh

Jochen Gerner

Werner Schairer

Klaus Gillessen

Christian Geng

Albert Marshall

A multilayer contact electrode for connecting a bonding wire to a p-type surface of a III/V-compound semiconductor is formed by a first metallizing step followed by a tempering step. Then, a second metallized layer of the same metal as the first metal layer is formed on the first layer but tempering of the second layer is avoided. A reliable bonding of a bonding wire to the non-tempered contact electrode is assured. The contact electrode includes a first inner metallized layer that is tempered and covered by a second nontempered metallized layer of the same metal as the first layer.

Multilayer contact electrode for compound semiconductors and production method thereof

A method for manufacturing a light emitting diode with the following process steps. Preparation of a substrate; production on the substrate of a series of layers which include the pn junction, that generates the radiation; production of contact layers on the surface of the layers including the pn junction and generating the radiation, and on the rear side of the substrate; and tempering of the contact layers. The method is characterized by the surface of the layers including the pn junction and generating the radiation being frosted or roughened before the contact layers are deposited. Through frosting the front side, it is possible to increase the luminous efficiency of the diodes by about 25%. Since the frost-etching process is performed before the contact layers are produced, this method can be used when aluminum is to be used as the contact material. Since the frosting is restricted to the front side of the diodes and the electrically active pn junction emerges to the surface at the lateral areas, the life of the diodes is not adversely affected by the method.

Method for the manufacture of a light emitting diode

In order to achieve lateral current spreading between a current injecting or current collecting surface of an electrode and an active surface of an active region in a semiconductor device such as a light emitting diode, a layered semiconductor heterostructure is arranged between the electrode and the active surface. The heterostructure includes at least two semiconductor layers forming a heterojunction therebetween, whereby the semiconductor layers are composed of different semiconductor materials or different compositional proportions of the same compound semiconductor. An enrichment region for the majority charge carriers is formed in one of the layers adjacent the heterojunction, and a majority charge carrier energy band discontinuity exists at the heterojunction. Each enrichment region provides a strong lateral current spreading effect, such that a stacked arrangement of plural heterojunction layer pairs brings about a strong step-wise lateral current spreading. The light output and efficiency of a light emitting diode is substantially improved by incorporating such a current spreading heterostructure.

Layered semiconductor structure for lateral current spreading, and light emitting diode including such a current spreading structure

A light emitting diode for generating preferably green light with improved luminous efficiency. A number of epitaxial layers suitable for the light emission is arranged on a doped semiconductor substrate wafer of GaP. The surface of the epitaxial layers is completely frosted. The light emission from the interior is considerably improved by the frosting. A contact layer structure is placed on the frosted surface for contacting the light emitting diode. The contact layer consists of several partial layers and covers at least a part the frosted surface. There is also a contact layer at the rear of the light emitting diode.

Light emitting diode with improved luminous efficiency having a contact

A method for manufacturing ohmic contacts on an n-doped semiconductor layer of a III-V compound semiconductor. An AuGeNi layer is formed on the n-type III-V compound semiconductor, where the thickness of the AuGeNi layer is between 50 and 200 nm and both the germanium and the nickel concentration in the AuGeNi layer are less than 1 percent by weight. An Au layer with a thickness of between 250 and 1000 nm is applied to the AuGeNi layer. These layers are not alloyed but tempered either at a temperature between 430.degree. and 480.degree. C. for a period between 5 and 20 seconds or at a temperature between 360.degree. and 400.degree. C. for a period between 40 and 180 minutes. The metal semiconductor contact produced in this way has a low contact resistance and is free from the inhomogeneities of alloyed AuGeNi contacts.

Method for manufacturing ohmic contacts for compound semiconductors

An light emitting diode of indium gallium aluminum phosphide with a substrate, an electrical contact to the substrate, a dual hetero structure as a active zone comprising a first cladding layer, an active layer and a second cladding layer to which, a window layer is applied, and to which in turn, an electrical contact is applied. This window layer is made of gallium aluminum phosphide.

Light emitting diode

The light-emitting diode consists of a substrate and a light-emission-generating layer located on the substrate and embedded between the cladding layers of a double heterostructure. On the top cladding layer, a current diffusion layer is located on which there is a further contact layer structure. The current diffusion layer is sufficiently thin so as to hardly absorb any light-emission. Thus, it can be economically produced by means of the MOCVD process. At the same time, the contact layer structure is provided with branched and finger-type electrodes for distributing the current together with the current diffusion layer onto the surface of the light-emission-generating layer. However, the structural size of the branched and finger-type electrodes is selected such that these can still be manufactured by the standard processes used in LED manufacture.

Light-emitting diode

A method for manufacture of radiation-emitting diodes includes manufacturing a layer sequence containing a radiation-generating pn-junction on a substrate wafer manufacturing contact layers for electrical connections on an upper face of the layer sequence and on an underside of the substrate wafer, etching trenches defining the size and shape of the area of individual pn-junctions of individual diodes being manufactured, providing a protective layer extending over the upper face contact layers and the etched trenches, subdividing the wafer having the layer sequence, the contact layers, and the protective layer thereon into individual diodes having lateral faces, after the subdividing, etching the lateral faces which are not provided with the protective layer to make the lateral faces into rough surfaces, and removing the protective layer following etching of the lateral faces.

Radiation-emitting diode with improved radiation output

A method for manufacturing ohmic contacts on an n-doped semiconductor layer of a III-V compound semiconductor wherein initially an AuGe layer is formed on the n-type III-V compound semiconductor, with the thickness of the AuGe layer being between 5 and 50 nm and the germanium concentration being less than 1% by weight. An Au layer with a thickness of between 200 and 600 nm is deposited on the AuGe layer. This layer sequence is now either tempered at a temperature of approx. 360.degree.-390.degree. C. for a period between 40 and 180 minutes, or undergoes rapid thermal annealing at a temperature between 430.degree. C. and 480.degree. C. for a period of 5-20 seconds. The metal semiconductor contact manufactured in accordance with the invention is free of inhomogeneities and has predominantly even boundary surfaces. Thanks to the low ohmic contact resistance and the high reflectivity for radiation in the near-infrared and visible wavelength ranges, the contact is particularly suitable as a full-surface rear contact for luminescent semiconductor diodes emitting infrared or visible light.

The invention relates to a heterostructure semiconductor laser diode with a layer sequence formed on a substrate, wherein a laser-active zone is arranged between layers of respectively opposite conductivity types, wherein an additional layer having a cover layer disposed thereon, and both of the same conductivity type as the substrate, are formed on the side of the layer sequence facing away from the substrate, and wherein a semiconductor area doped oppositely to the cover layer is produced by diffusion in the cover layer and penetrates, in a strip-shaped zone extending perpendicularly to the exit surface of the laser radiation in the area of the plane of symmetry below a v-groove-shaped recess, the boundary plane between the cover layer and the adjacent additional layer and extends into but not through the layer arranged thereunder, whereby the current flowing in the forward direction of the semiconductor laser diode is confined to a narrow strip-shaped area of the laser-active layer. The amplifying area of the laser-active is made significantly shorter in its length-wise dimensions than the resonator length of the semiconductor laser diode by the laser-active layer extending in a small area of the resonator length immediately in front of the two mirrors of the semiconductor laser diode at an incline to the main plane of the laser-active layer and by the v-groove-shaped recess being symmetrically shortened by the amount of this small area in relation to the resonator length.

Heterostructure semiconductor laser diode

The invention relates to a heterostructure semiconductor laser diode with a layer sequence formed on a substrate, wherein the layer sequence includes a laser-active zone arranged between layers of respectively opposite conductivity types, and an additional layer and having a cover layer disposed thereon, and both of the same conductivity type as the substrate, formed on the side of the layer sequence facing away from the substrate, and wherein the cover layer includes an oppositely doped semiconductor area which, in a stripe-shaped surface region extending perpendicularly to the exit surface of the laser radiation in the area of the axis of symmetry, and through a v-groove-shaped recess penetrates, the boundary plane between the cover layer and the adjacent additional layer and extends into the layer located thereunder, whereby the current flowing in the forward direction of the semiconductor laser diode is confined to a narrow, strip-shaped area of the laser-active zone. Higher output power and greater long-term stability are attained by the v-groove-shaped recess being made shorter in its longitudinal dimensions than the resonator length and by the laser-active zone being simultaneously highly doped.

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Wiesloch, Germany

Jochen Gerner