Micro LED Regrowth Structure for Etched Mesa Sidewall Defects
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Solution Overview
Problem
Surface defect states at the sidewalls of micro LEDs, particularly in the active layer, lead to nonradiative recombination of holes and electrons, reducing the internal quantum efficiency of these devices.
Innovation Solution
A regrown semiconductor passivation layer is used to mitigate defects on the sidewalls of the mesa pillar structure, which can be formed through various etching and cleaning operations, either ex situ or in situ within the reaction chamber, to enhance the radiative efficiency of micro LEDs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If etching techniques are used to form mesa pillar structure, then the LED structure is defined and shaped, but surface defect states are created at sidewalls leading to nonradiative recombination
Solution Approach 1:
A regrowth layer is deposited conformally over the mesa pillar structure before final device completion. This preliminary regrowth action passivates the sidewall surface defects created during etching, preventing nonradiative recombination pathways before they can degrade device performance.
Solution Approach 2:
The regrowth layer acts as an intermediary between the etched mesa sidewalls and the active LED structures. This intermediate layer provides a passivation interface that reduces surface state density, thereby mitigating the harmful effects of etching-induced defects while maintaining the desired mesa geometry.
2Manufacturing precision
If multiple etching operations are performed to define the mesa structure, then manufacturing precision is improved, but surface contamination and oxidation increase
Solution Approach 1:
The regrowth layer is deposited as a preliminary protective action after etching operations and before subsequent processing steps. This layer prevents oxidation and contamination of the freshly etched surfaces, preserving the quality of multi-step etched structures.
Solution Approach 2:
The regrowth process converts the harmful exposed surfaces created by multiple etching operations into beneficial passivated interfaces. The regrowth layer incorporates into the existing structure, transforming contaminated sidewalls into protected, electrically active surfaces that enhance rather than degrade device performance.
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 regrown semiconductor passivation layer effectively reduces nonradiative recombination, improving the internal quantum efficiency and overall performance of micro LEDs by addressing surface defects and contamination.
Implementation Method 1
a regrown semiconductor passivation layer is used to passivate the sidewalls of the mesa pillar structure
Implementation Method 2
surface defect states created at micro LED sidewalls, and more particularly sidewalls of the active layer, can lead to nonradiative recombination of holes and electrons
Data Source
AI summary
Light emitting diodes with regrown semiconductor layers and methods of manufacture are described. In an embodiment, a light emitting diode includes a base structure including a first cladding layer doped with a first dopant type (e.g. n-type) and step surface. A mesa pillar including an active layer protrudes from the step surface, and a regrown second cladding layer doped with a second dopant type (e.g. p-type) is in direct contact with and spans a bottom surface and sidewalls of the mesa pillar and the step surface.