LED Double-Layer Contact Structure for Voltage Reduction
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Solution Overview
Problem
Conventional light-emitting diode (LED) devices experience increased working voltage due to patterning of the p-type second confining layer, which also complicates the fabrication process and increases product costs.
Innovation Solution
The LED device incorporates a double-layered contact structure with thin, patterned contact layers of heavy-doped materials, such as gallium indium nitride or divalent phosphorous doped gallium nitride, to enhance ohmic contact area and reduce working voltage, while simplifying the fabrication method by using techniques like wet-etching or ICP etching to form openings and expose the contact layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the p-type second confining layer is patterned to enhance light extraction efficiency, then the lighting brightness is increased, but the working voltage is relatively increased
Solution Approach 1:
The contact structure is segmented into multiple layers: a first contact layer in direct contact with the p-type second confining layer, and a second contact layer positioned between the first contact layer and the transparent electrically conductive layer. This segmentation allows each layer to perform specialized functions, with the first contact layer providing low-resistance ohmic contact to reduce working voltage, while the second contact layer and transparent electrically conductive layer maintain light extraction efficiency through their optical properties.
Solution Approach 2:
The first contact layer acts as an intermediary between the p-type second confining layer and the rest of the contact structure. By introducing this intermediate layer with optimized electrical properties, the patent achieves low working voltage through improved ohmic contact while the second contact layer and transparent electrically conductive layer continue to facilitate light extraction, thus resolving the contradiction between reducing working voltage and maintaining brightness.
2Loss of energy
If the p-type second confining layer is patterned to enable sufficient contact, then the light extraction efficiency is enhanced, but the fabrication process is complicated and product cost is increased
Solution Approach 1:
The contact structure is divided into multiple functional layers that can be processed independently. The first contact layer is formed directly on the p-type second confining layer, while the second contact layer and transparent electrically conductive layer are formed subsequently. This segmentation simplifies the fabrication process by allowing each layer to be optimized and processed separately, reducing the overall complexity compared to patterning the confining layer itself.
Solution Approach 2:
Instead of modifying the p-type second confining layer in the horizontal dimension (patterning), the patent introduces additional contact layers in the vertical dimension. This dimensional shift allows light extraction efficiency to be enhanced through the optical properties of the second contact layer and transparent electrically conductive layer, while avoiding the fabrication complexity associated with patterning the confining layer.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively lowers the working voltage of the LED device, improves light-extraction efficiency, and reduces production costs by increasing the contact area and simplifying the fabrication process.
Implementation Method 1
a first electrically conductive contact layer on the first confining layer; a second confining layer of the second type of electrical conductivity patterned and located on the first electrically conductive contact layer; a second electrically conductive contact layer patterned and located on the second confining layer
Implementation Method 2
a transparent electrically conductive layer on the second electrically conductive contact layer, the transparent electrically conductive layer having a plurality of contacts passing through the second electrically conductive layer and the second confining layer to electrically contact with the first electrically conductive contact layer
Implementation Method 3
The current flowing from the second electrode 17b into the light-emitting diode device 1 is uniformly distributed whereby the electron and the hole are combined within the active layer 13 so that the energy is released and converted into light energy for light-emitting
Data Source
AI summary
The present invention provides a light-emitting diode (LED) device and a fabrication method thereof. The LED device has a double-layered contact layer structure with a surface of one contact layer being patterned to increase ohmic contact area of the double-layered contact layer structure to lower an operation voltage of the LED device, and hence reducing power consumption.