GaN LED Conductive Mask Layer for Current Spreading
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Solution Overview
Problem
GaN-based light-emitting diodes experience current blockage due to poor current spreading capacity, leading to voltage rise and efficiency loss, particularly in high-current and high-luminance applications, as existing solutions like n-type spreading fingers require removal of p-type semiconductor layers, narrowing the light-emitting area and reducing luminance.
Innovation Solution
A light-emitting diode structure featuring a conductive mask layer over the substrate with an epitaxial laminated layer and current channels that allow current to spread horizontally, improving uniformity and reducing working voltage, while maintaining light emission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If n-type spreading fingers are added to improve current spreading uniformity, then current spreading uniformity is improved, but light-emitting area is reduced and luminance is lost
Solution Approach 1:
The patent introduces a conductive mask layer positioned between the substrate and the epitaxial laminated layer, creating a new dimensional level for current distribution. This conductive mask layer acts as an intermediate current distribution plane that spreads current horizontally before it enters the vertical epitaxial structure, thereby improving current spreading uniformity without requiring removal of the p-type semiconductor layer and without reducing the light-emitting area.
2Reliability
If multiple n-type spreading fingers are used in large-power LED chips, then current blockage effect is reduced, but luminance loss increases and photoelectric efficiency decreases
Solution Approach 1:
The conductive mask layer performs preliminary current spreading action before the current enters the epitaxial laminated layer. By distributing the current horizontally across the conductive mask layer in advance, the patent prevents current blockage effects from occurring in the subsequent vertical current path through the p-type and n-type semiconductor layers, thereby maintaining high luminance and photoelectric efficiency without requiring multiple n-type spreading fingers.
3Device complexity
If current is injected directly into the epitaxial laminated layer, then device structure is simple, but current spreading uniformity is poor and working voltage is high
Solution Approach 1:
The conductive mask layer serves as an intermediary element between the substrate and the epitaxial laminated layer. It mediates the current distribution by providing a highly conductive horizontal spreading plane that evenly distributes current before it enters the vertical epitaxial structure, thereby improving current spreading uniformity and reducing working voltage while maintaining relatively simple device structure.
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 proposed structure effectively enhances current spreading uniformity and reduces working voltage, maintaining high luminance and photoelectric efficiency even in large-power LED chips, by directing current through conductive mask layers with higher conductivity than nitride materials.
Implementation Method 1
a conductive mask layer is planted over the substrate surface... current is firstly conducted to the conductive mask layer through the current channel, and then to the epitaxial laminated layer after horizontal spreading over the conductive mask layer
Implementation Method 2
An epitaxial laminated layer is formed over the conductive mask layer via epitaxial growth
Data Source
AI summary
A light-emitting diode includes a conductive mask layer planted over a substrate surface. An epitaxial laminated layer is formed over the conductive mask layer via epitaxial growth; and a current channel is formed over the epitaxial laminated layer; during injection, current is firstly conducted to the conductive mask layer through the current channel, and then to the epitaxial laminated layer after horizontal spreading over the conductive mask layer, which effectively improves current spreading uniformity and reduces working voltage of device. Meanwhile, the conductive mask layer reflects light to further improve extraction efficiency and light-emitting luminance.