Recessed Semiconductor Stack for LED Hole Injection and Reliability
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Solution Overview
Problem
Current semiconductor stacks face limitations in light-emitting efficiency and reliability due to intrinsic physical constraints, such as dislocation defects and non-radiative recombination, especially under high temperature or high current conditions, which affect the performance of light-emitting diodes.
Innovation Solution
The semiconductor stack incorporates recesses in the active region, with a recess-induced layer between the first-type semiconductor layer and the active region, optimizing the position and size of these recesses to enhance hole injection, current spreading, and reduce dislocation defects, thereby improving light-emitting efficiency and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If recesses are added to the active region to improve hole injection and current spreading, then light-emitting efficiency is improved, but device complexity increases
Solution Approach 1:
The active region is segmented by introducing multiple recesses that extend from the upper surface toward the lower surface, dividing the active region into distinct zones. This segmentation creates multiple current spreading paths and enhances hole injection at different locations, thereby improving light-emitting efficiency while managing structural complexity through systematic division
Solution Approach 2:
The recesses introduce a vertical dimension to the current spreading mechanism by extending from the upper surface toward the lower surface of the active region. This three-dimensional structure enables current to spread through multiple depth levels, enhancing hole injection and light-emitting efficiency without merely expanding the planar area
2Reliability
If the recess depth is increased to reduce dislocation defects, then reliability is improved, but manufacturing precision requirements increase
Solution Approach 1:
The recess depth is controlled within a specific parameter range (0.5-0.9 times the active region thickness) to optimize the balance between reliability improvement through dislocation defect reduction and manufacturing precision requirements. This parameter optimization ensures sufficient depth to reach and mitigate dislocation defects while maintaining manufacturability
Solution Approach 2:
The recess-induced layer acts as an intermediary structure between the first-type semiconductor layer and the active region, facilitating the transition and helping to manage dislocation defects. This intermediate layer provides a gradual transition zone that reduces the stress concentration and dislocation propagation while simplifying the manufacturing process
3Productivity
If recesses are introduced to enhance current spreading, then light-emitting efficiency is improved, but the manufacturing process complexity increases
Solution Approach 1:
The recesses are formed in the active region before final device assembly and operation. This preliminary structuring of the active region with controlled-depth recesses establishes the current spreading pathways in advance, enabling improved light-emitting efficiency while allowing subsequent manufacturing steps to proceed with standard processes
Data Source
AI summary
A semiconductor stack includes a first-type semiconductor layer, a second-type semiconductor layer, an active region located between the first-type semiconductor layer and the second-type semiconductor layer, one or multiple recesses, and a recess-induced layer located between the first-type semiconductor layer and the active region. The active region has a first thickness and includes an upper surface and a lower surface closer to the first-type semiconductor layer than the upper surface. Each recess includes a bottom disposed in the active region. A first distance is from the bottom of the recess to the lower surface. The first distance is 0.5-0.9 times the first thickness.