Active Matrix Micro LED Array With Monolithic HEMT Driving
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Solution Overview
Problem
Current micro LED array production methods face challenges in integration with active matrix electronic circuitry, particularly in achieving high electron mobility and efficient current driving due to limitations in semiconductor materials and fabrication processes.
Innovation Solution
The integration of a common undoped Group III-nitride semiconductor layer with high electron mobility transistors (HEMTs) and a 2T+1C circuitry structure, where each transistor-driven LED precursor includes a monolithic LED structure with a barrier layer inducing a two-dimensional electron channel and a gate contact encircling the LED, enhancing current modulation and driving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If pick and place technique is used to assemble micro LEDs onto substrate, then different LED properties can be selected and faulty devices discarded, but pick and place accuracy and transfer time are severely affected by required resolution and array size
Solution Approach 1:
The patent combines the LED array fabrication and active matrix circuitry integration into a single monolithic growth process on a common substrate. This merging eliminates the separate pick-and-place assembly step, thereby resolving the contradiction by maintaining LED property versatility through selective growth regions while dramatically improving productivity by removing the time-consuming transfer process.
2Productivity
If monolithic integration is used to fabricate micro LED array from same growth substrate, then integration density and array resolution are improved, but colourisation techniques required for full colour displays become more complex
Solution Approach 1:
The patent applies local quality by creating selectively doped regions and distinct semiconductor layers in specific areas of the monolithic structure. Different regions of the substrate are grown with different doping concentrations and material compositions to simultaneously achieve high integration density and enable color differentiation through localized property variations rather than complex post-growth colorization.
3Ease of manufacture
If conventional semiconductor materials and processes are used for micro LED array, then manufacturing is simpler, but electron mobility and current driving efficiency are insufficient for active matrix circuitry integration
Solution Approach 1:
The patent employs composite semiconductor structures combining different Group III-nitride materials (GaN, AlGaN, InGaN) with varying doping concentrations in a monolithic architecture. This composite approach maintains compatibility with conventional manufacturing processes while achieving superior electron mobility through material composition optimization and heterostructure design, particularly in the driver transistor regions.
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 approach improves the performance and integration of active matrix circuitry with the LED array, reducing processing complexity and enhancing electrical performance by utilizing high electron mobility transistors and efficient current distribution across the array.
Implementation Method 1
The barrier semiconducting layer is formed on a portion of the common semiconducting layer encircling the monolithic LED structure and is configured to induce a two-dimensional electron channel layer at the interface between the common semiconducting layer and the barrier semiconducting layer
Implementation Method 2
The gate contact is formed over a portion of the two-dimensional electron channel, wherein the gate contact encircles the LED structure
Implementation Method 3
The common source contact is configured to form an ohmic contact to each two-dimensional electron channel such that a high electron mobility transistor is provided between the common source contact and each monolithic LED structure
Implementation Method 4
Each monolithic LED structure comprises a plurality of III-nitride semiconducting layers
Data Source
AI summary
An active matrix LED array precursor forming a precursor to a micro LED array is provided. The active matrix LED array precursor comprises a common first semiconducting layer comprising a substantially undoped Group III-nitride, a plurality of transistor-driven LED precursors, and a common source contact. Each transistor-driven LED precursor comprises a monolithic light emitting diode (LED) structure comprising a plurality of III-nitride semiconducting layers, a barrier semiconducting layer, and a gate contact. Each monolithic LED structure is formed on a portion of the common semiconducting layer. The barrier semiconducting is layer formed on a portion of the common semiconducting layer encircling the LED structure and configured to induce a two-dimensional electron channel layer at the interface between the common semiconducting layer and the barrier semiconducting layer. The gate contact is formed over a portion of the two-dimensional electron channel layer, the gate contact encircling the LED structure. The common source contact is configured to form an ohmic contact to each portion of the two-dimensional electron channel layer such that a high electron mobility transistor is provided between the common source contact and each monolithic LED structure for driving each LED structure.