Micro LED Mesa Edge Structure Using Schottky Depletion Control
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Solution Overview
Problem
Micro LEDs suffer from low efficiency due to non-radiative recombination at the mesa edges, which generates heat instead of light, reducing the overall lighting efficiency.
Innovation Solution
A micro LED element is designed with a mesa structure including a first semiconductor layer, a light emitting layer, and a second semiconductor layer, stacked from top down, along with a passivation layer on the sidewall and a Schottky metal layer adjacent to the passivation layer, which creates a depletion region in the light emitting layer to reduce non-radiative recombination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the mesa size is reduced to increase resolution, then the resolution is improved, but the mesa edges become more susceptible to damage and non-radiative recombination increases
Solution Approach 1:
The patent applies local quality by introducing a Schottky metal layer specifically at the mesa edges where non-radiative recombination occurs. This creates a localized depletion region that prevents carrier leakage at the problematic edge areas, while leaving the bulk of the light emitting layer intact for efficient light generation. The passivation layer is also applied locally on the sidewall surface to protect the mesa structure.
Solution Approach 2:
The Schottky metal layer acts as an intermediary element between the damaged mesa edges and the light emitting layer. It creates a depletion region that serves as a protective barrier, preventing carriers from reaching the damaged mesa edges where they would otherwise undergo non-radiative recombination. This intermediary structure allows the micro LED to maintain high resolution with small mesa sizes while preserving lighting efficiency.
2Measurement precision
If etching is used to form small mesas, then the resolution is improved, but the mesa edges are damaged reducing efficiency
Solution Approach 1:
The patent applies preliminary action by forming the Schottky metal layer and passivation layer on the mesa structure after etching. This protective structure is introduced in advance to prevent further damage to the already etched mesa edges and to immediately begin preventing non-radiative recombination. The depletion region is created before the device is fully operational, ensuring protection from the start.
3Measurement precision
If the mesa size is reduced, then the resolution and color gamut are improved, but the thermal effects worsen due to increased non-radiative recombination
Solution Approach 1:
The patent converts the harmful effect of small mesa edges (which cause non-radiative recombination and heat generation) into a beneficial structured approach. By intentionally introducing the Schottky metal layer and passivation layer, the design acknowledges the edge damage issue and creates a controlled depletion region that manages carrier flow. This transforms the problematic edge areas from heat-generating defects into controlled structures that protect the light emitting layer.
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 implementation of the Schottky metal layer and passivation layer significantly reduces non-radiative recombination at the mesa edges, enhancing the lighting efficiency of micro LEDs by increasing the proportion of radiative recombination, which produces visible light.
Implementation Method 1
a Schottky metal layer disposed adjacent to the passivation layer, wherein the Schottky metal layer creates a depletion region at least in the light emitting layer
Data Source
AI summary
A micro LED display panel includes a mesa including a first semiconductor layer, a light emitting layer, and a second semiconductor layer that are stacked from top down; a passivation layer formed on a sidewall surface of the mesa; and a Schottky metal layer disposed adjacent to the passivation layer, wherein the Schottky metal layer creates a depletion region at least in the light emitting layer.