LED Mesa Electrode Layout for Current Spreading and Carrier Confinement
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Solution Overview
Problem
Maintaining optoelectronic properties becomes challenging as light-emitting diodes (LEDs) are miniaturized, necessitating improvements in electrode design to ensure efficient current distribution and reduce non-radiative recombination at the sidewalls.
Innovation Solution
A semiconductor element design featuring a mesa portion with a recessed portion, a contact layer, and an insulating layer with openings, along with electrode layers positioned to minimize overlap and optimize current spreading, thereby enhancing carrier confinement within the active layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the LED size is reduced for miniaturization, then the device compactness is improved, but the optoelectronic properties deteriorate
Solution Approach 1:
The contact layer is designed with non-uniform width, being wider at the mesa portion and narrower at the recessed portion. This local variation in geometry allows different regions of the contact layer to serve different functions: the wider mesa portion provides good electrical contact while the narrower recessed portion minimizes sidewall area where non-radiative recombination occurs, thus maintaining optoelectronic properties in a miniaturized device
Solution Approach 2:
The contact layer exhibits asymmetric width distribution across the mesa and recessed portions. By making the contact layer width dependent on the horizontal position (wider at mesa, narrower at recessed portion), the design creates an asymmetric structure that optimizes both electrical contact and carrier confinement, resolving the contradiction between miniaturization and optoelectronic performance
2Reliability
If the contact layer area is reduced to improve carrier confinement, then the external quantum efficiency is improved, but the current distribution becomes uneven
Solution Approach 1:
The contact layer is designed with spatially varying width, being wider at the mesa portion and narrower at the recessed portion. This local quality variation allows the contact layer to simultaneously achieve good electrical contact (wider mesa portion) and effective carrier confinement (narrower recessed portion), resolving the contradiction between current distribution uniformity and external quantum efficiency
Solution Approach 2:
The contact layer design transitions from a two-dimensional uniform structure to a three-dimensional structure with varying width across different horizontal positions. This dimensional variation allows the contact layer to optimize both electrical contact area and carrier confinement in different regions, achieving uniform current distribution while maintaining high external quantum efficiency
3Loss of energy
If the electrode layers are positioned to minimize overlap, then the non-radiative recombination is reduced, but the current spreading becomes inefficient
Solution Approach 1:
The contact layer is designed with non-uniform width, being wider at the mesa portion and narrower at the recessed portion. This local variation allows the contact layer to simultaneously achieve good electrical contact (wider mesa portion) and effective carrier confinement (narrower recessed portion), resolving the contradiction between current spreading efficiency and non-radiative recombination
Solution Approach 2:
The contact layer is segmented into different regions with different widths corresponding to the mesa and recessed portions. This segmentation allows each region to perform its specific function: the mesa portion handles current injection while the recessed portion confines carriers, thus reducing non-radiative recombination while maintaining current spreading efficiency
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
This design improves photoelectric conversion efficiency and reduces non-radiative recombination, achieving higher external quantum efficiency under specific current densities.
Implementation Method 1
a contact layer (18) disposed on the second semiconductor layer (122) of the mesa portion (M)... an electrode layer (20, 30) disposed on the insulating layer (50), wherein the electrode layer is electrically connected to the contact layer (18)
Implementation Method 2
the light-emitting diode includes a substrate, an n-type semiconductor layer, an active layer, and a p-type semiconductor layer formed on the substrate... When the light-emitting diode is driven by a forward bias through the electrodes, the holes from the p-type semiconductor layer and the electrons from the n-type semiconductor layer combine in the active layer to emit the light
Data Source
AI summary
A semiconductor element is provided. The semiconductor element includes: a semiconductor stack including a mesa portion and a recessed portion; a contact layer formed on the mesa portion; an insulating layer formed on the semiconductor stack and the contact layer, wherein the insulating layer includes a first opening formed on the mesa portion; and an electrode layer formed on the insulating layer, wherein the electrode layer is electrically connected to the contact layer. In a plan view, the mesa portion includes a first centroid, the contact layer includes a second centroid, and the first opening includes a third centroid, and a distance between the first centroid and the third centroid is greater than a distance between the second centroid and the third centroid.