Agilent Technologies, Inc.

Hewlett-packard Company

Philips Lumileds Lighting Company LLC

Lumileds Lighting U.s., LLC

Mark R Hueschen

Tetsuya Takeuchi

Ghulam Hasnain

James R Sheats

David P Bour

Daniel Bernardo Roitman

Nathan Fredrick Gardner

Werner K Goetz

Stephen Andrew Stockman

Nicolas J Moll

Christopher P Kocot

Scott W Corzine

Richard P Schneider

Sandeep Raj Bahl

Ronald L Moon

Karen L Seaward

Danny E Mars

George Andrew Briggs

Marek E Mierzwinski

A light emitting device in accordance with an embodiment of the present invention includes a first semiconductor layer of a first conductivity type having a first surface, and an active region formed overlying the first semiconductor layer. The active region includes a second semiconductor layer which is either a quantum well layer or a barrier layer. The second semiconductor layer is formed from a semiconductor alloy having a composition graded in a direction substantially perpendicular to the first surface of the first semiconductor layer. The light emitting device also includes a third semiconductor layer of a second conductivity type formed overlying the active region.

Light emitting diodes with graded composition active regions

A display having a plurality of light emitting pixels. Each pixels includes an isolation transistor, a driving circuit, and an organic light emitting diode (OLED). The driving circuit storing a value that determines the magnitude of the light emitted by that pixels, the driving circuit placing the OLED in a conducting path between the first and second power terminals. The driving circuit is programmed through the isolation transistor. In one embodiment of the present invention, the driving circuit includes a storage capacitor and a driving transistor. The OLEDs are part of an array of OLEDs. The array of OLEDs is constructed on a flexible sheet having first and second surfaces, the flexible sheet being transparent to light of a first wavelength. A transparent first electrode layer is in contact with the first surface. A light emitting layer including an organic polymer is in contact with the first electrode layer. A plurality of second electrodes, one such second electrode corresponding to each of the OLEDs, is in contact with the light emitting layer. Each second electrode has an isolated conducting area. The driving transistor are part of a transistor array having a plurality of connection points disposed on a surface, each connection point corresponding to one of the second electrodes in the array of OLEDs. The connection points are arranged such that each second electrode overlies the corresponding connection point when the array of OLEDs is properly aligned with the transistor array. The connection points are bonded to the corresponding second electrodes by a bonding layer.

Method of manufacture of active matrix addressed polymer LED display

A novel tunnel structure is described that enables tunnel diode behavior to be exhibited even in material systems in which extremely heavy doping is impossible and only moderate or light doping levels may be achieved. In one aspect, the tunnel heterostructure includes a first semiconductor layer, a second semiconductor layer, and an intermediate semiconductor layer that is sandwiched between the first and second semiconductor layers and forms first and second heterointerfaces respectively therewith. The first and second heterointerfaces are characterized by respective polarization charge regions that produce a polarization field across the intermediate semiconductor layer that promotes charge carrier tunneling through the intermediate semiconductor layer. In another aspect, the invention features a semiconductor structure having a p-type region, and the above-described heterostructure disposed as a tunnel contact between the p-type region of the semiconductor structure and an adjacent n-type region.

Polarization field enhanced tunnel structures

An optical semiconductor device having an active layer for generating light via the recombination of holes and electrons therein. The active layer is part of a plurality of semiconductor layers including an n-p junction between an n-type layer and a p-type layer. The active layer has a polarization field therein having a field direction that depends on the orientation of the active layer when the active layer is grown. In the present invention, the polarization field in the active layer has an orientation such that the polarization field is directed from the n-layer to the p-layer.

Efficiency GaN-based light emitting devices

A heterojunction bipolar transistor (HBT), including an emitter formed from a first semiconductor material, a base formed from a second semiconductor material, and a grading structure between the emitter and the base is disclosed. The grading structure comprises a semiconductor material containing at least one element not present in the first and second semiconductor materials, where the grading structure has a conduction band energy substantially equal to a conduction band energy of the base at an interface between the base and the grading structure, and where the grading structure has a conduction band energy substantially equal to a conduction band energy of the emitter at an interface between the emitter and the grading structure.

Heterojunction bipolar transistor (HBT) having improved emitter-base grading structure

A barrier for preventing water or oxygen from a source thereof from reaching a device that is sensitive to water or oxygen. The barrier is constructed by depositing a first polymer layer between the device and the source. An inorganic layer is deposited on the first polymer layer of the device by plasma enhanced chemical vapor deposition utilizing an electron cyclotron resonance source ECR-PECVD. A second polymer layer is then deposited on the inorganic layer. The inorganic layer is preferably an oxide or nitride. A second barrier layer having a compound that absorbs oxygen or water can be placed between the inorganic layer and the device to further retard the passage of oxygen or water. The present invention is particularly useful in encapsulating electroluminescent displays.

Transparent, flexible permeability barrier for organic

A device for a light detection system includes an electroluminescent layer stack on a transparent member, such as a glass substrate, with at least one layer of the layer stack being patterned to define first and second electroluminescent regions spaced apart by a transparent light collection path for passage of backreflected light. The layer stack includes first and second electrode layers on opposed sides of one or more active layers. In one embodiment, the second electrode layer is the only layer that is patterned to define the light collection path. In this embodiment, the other layers extend continuously across the light collection path. In another embodiment, all of the layers are patterned to form a gap between the first and second electroluminescent regions. The layer stack is hermetically sealed to protect the active layer or layers from atmosphere-induced degradation. An illumination collector is aligned with the light collection path to receive light that is backreflected from a surface of interest through the light collection path. The illumination collector may be an optical arrangement, a photodetector, or both. In the preferred embodiment, the electroluminescent layer stack is an organic light-emitting source.

Electroluminescent device and fabrication method for a light detection

An improved electroluminescent device which includes a hole injection electrode, an electron injection electrode, and an electroluminescent layer located between the hole and electron injection electrodes. The electroluminescent layer includes an organic polymer and a hindered phenolic additive in a concentration greater than 4% by weight. The preferred organic polymer is a derivative of PPV. The preferred hindered phenolic additives are and 2,4,6 tri-tert-butyl phenol 2,6 di-tert-butyl-methylphenol. The device has higher efficiency and a slower rate of degradation than devices lacking the hindered phenolic additive.

Polymer-based electroluminescent device with improved stability

A charge injection transistor is a real-space electron transfer heterostructure with several novel features. The channel layer is comprised of In.sub.0.25 Ga.sub.0.75 As supported by a buffer layer of Al.sub.0.3 Ga.sub.0.7 As resting on the substrate. A barrier layer comprised of Al.sub.0.1 Ga.sub.0.9 As overlays the channel layer. Over this barrier is a layer of GaAs forming the electron drift region. The collector electrode is located on top of this drift layer, between the source and heater electrodes, which extend downward through the drift and barrier layers and create the electric field in the channel layer. Positive voltages are applied to the heater and collector, relative to the source. Electrons flow through the channel region and become heated. At sufficiently high temperature they escape over the barrier and travel through the drift region to the collector. In comparison with previous devices, the use of InGaAs in the channel layer provides a deeper quantum well for the conduction electrons, and suppresses leakage through the barrier at room temperatures. The collector drift layer has a short transit time delay. The location of the collector reduces parasitic leakage from the source, and the collector capacitance is small. These features enhance the high frequency performance of the device. The limiting power gain frequency and current gain frequency are at least twice the corresponding values attained in previous devices.

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Palo Alto, CA, United States of America

Mark R Hueschen