GaN LED Resistivity Gradient Current Confinement
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Solution Overview
Problem
GaN-based LEDs suffer from efficiency and stability issues due to threading dislocation defects caused by lattice mismatch between the substrate and growth alloy, which reduce their performance.
Innovation Solution
A light-emitting diode (LED) design featuring a first type semiconductor layer with a low resistance portion and a high resistance portion, where the active layer has regions with varying threading dislocation densities, and a method involving dislocation-controlling features and resistivity gradient formation to enhance current confinement and luminous efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If threading dislocation defects are present in GaN-based LEDs due to lattice mismatch, then manufacturing is simplified, but efficiency and stability deteriorate
Solution Approach 1:
The semiconductor layer is divided into multiple regions with different resistivity values, creating distinct functional zones. Low resistivity regions confine current while high resistivity regions guide dislocations away from the active area, allowing simultaneous management of electrical and mechanical properties without compromising manufacturing simplicity
Solution Approach 2:
Different regions of the semiconductor layer are assigned different resistivity characteristics tailored to their specific functions. The active region uses low resistivity for current confinement, while edge regions use high resistivity for dislocation management, optimizing local properties to resolve the contradiction between manufacturing ease and device reliability
2Ease of manufacture
If current is spread uniformly across the active layer, then manufacturing is simple, but luminous efficiency deteriorates due to threading dislocations
Solution Approach 1:
The semiconductor layer implements spatially varying resistivity with low resistivity in the active region and high resistivity at edges, creating localized current confinement exactly where needed in the active area while maintaining simple overall manufacturing processes
Solution Approach 2:
The patent converts the harmful effect of threading dislocations into a beneficial guide by using high resistivity edge regions to channel dislocations away from the active area, while simultaneously using low resistivity regions to confine current precisely within the active region, thereby improving luminous efficiency without complex manufacturing
3Productivity
If high current density is applied to improve luminous efficiency, then brightness increases, but operating stability deteriorates due to defect regions
Solution Approach 1:
Low resistivity regions are strategically placed in areas requiring high current density for luminous efficiency, while high resistivity regions are positioned at edges to protect against dislocation-induced instability, allowing the device to operate at high efficiency with improved stability
Solution Approach 2:
The semiconductor layer is segmented into functionally distinct regions that can independently optimize for their specific purposes: current confinement for efficiency and dislocation management for stability, resolving the contradiction between high current density operation and operating stability
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 increases current density and luminous efficiency by confining the current within specific regions of the active layer, improving the operating stability and efficiency of the LED.
Implementation Method 1
the resistivity of the first type semiconductor layer is increased from the low resistance portion toward the high resistance portion
Implementation Method 2
Light emitting diodes (LEDs) are semiconductor light-emitting devices which convert electricity into light energy
Data Source
AI summary
A light-emitting diode (LED) includes a first type semiconductor layer, a second type semiconductor layer, and an active layer. The first type semiconductor layer includes a low resistance portion and a high resistance portion. The low resistance portion is separated from at least one edge of the first type semiconductor layer by the high resistance portion, and the resistivity of the first type semiconductor layer is increased from the low resistance portion toward the high resistance portion. The active layer is disposed between the first type semiconductor layer and the second type semiconductor layer. The active layer has a first region and a second region, in which the first region has a threading dislocation density greater than that of the second region, and a vertical projection of the low resistance portion on the active layer at least partially overlaps with the second region.