Micro-LED Oxide Ring Structure for Higher PN Junction Current Density
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Solution Overview
Problem
Conventional LED display technologies face challenges in achieving high light efficiency, reliable fabrication, and low power consumption, particularly in the integration of micro-LEDs with pixel driver circuits, which results in inefficient and costly manufacturing processes and reliability issues due to thermal mismatch and light cross-talk.
Innovation Solution
The development of a multi-color LED device structure that integrates multiple micro-LED structures in a stacked configuration within a pixel area, allowing light from one LED to pass through others to produce combined colors, with a reduced substrate presence to minimize cross-talk and stress, and the use of oxidized layers to enhance light emission efficiency by confining current flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional LED fabrication methods are used with separate substrates for LEDs and control circuitry, then manufacturing flexibility is maintained, but fabrication efficiency is low and cost is high due to pick-and-place processes
Solution Approach 1:
The patent merges the LED fabrication process with the control circuitry fabrication by bonding the LED array substrate directly to the control circuitry substrate in an aligned manner, eliminating the need for separate pick-and-place operations and intermediate substrates, thereby improving fabrication efficiency and manufacturing speed
Solution Approach 2:
The bonding process serves multiple functions simultaneously: it transfers the LED array to the control circuitry substrate, establishes electrical connections, and provides mechanical support, reducing the number of separate manufacturing steps required
2Strength
If the substrate on which LEDs are fabricated is retained in the final product, then structural support is maintained, but light cross-talk occurs between adjacent pixels
Solution Approach 1:
The patent removes the original LED substrate from the final product after bonding the LED array to the control circuitry substrate, eliminating the source of light cross-talk while maintaining structural support through the bonding interface and control circuitry substrate
Solution Approach 2:
The control circuitry substrate serves as an intermediary that provides both structural support and electrical connectivity while allowing light to pass through without cross-talk, replacing the original substrate's support function without its harmful optical properties
3Reliability
If metal bonding is used to align and bond LED array to control circuitry, then electrical connection is established, but thermal mismatch generates stress at the bonding interface
Solution Approach 1:
The patent employs a composite bonding structure that combines metal bonding layers with additional materials designed to accommodate thermal expansion differences, reducing thermal stress at the bonding interface while maintaining reliable electrical connections
Solution Approach 2:
The bonding process parameters are optimized to control the bonding strength and thermal properties, and the bonding layer composition is adjusted to match thermal expansion coefficients, reducing thermal mismatch stress while ensuring reliable electrical connection
4Manufacturing precision
If multiple micro-LED structures are integrated in a pixel area, then color resolution is improved, but current flow density becomes insufficient
Solution Approach 1:
The patent transitions from planar current distribution to three-dimensional current confinement by using vertical oxide layers that channel current through specific pathways, increasing current flow density to the micro-LED structures while maintaining high color resolution through the stacked configuration
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 light emission efficiency, simplifies the LED pixel structure, reduces damage to epitaxial layers, and enhances the reliability of micro-LED fabrication, while maintaining low power consumption and enabling efficient mass production of high-resolution displays.
Implementation Method 1
oxidized layers to enhance light emission efficiency by confining current flow
Implementation Method 2
light emitting diode (LED) is a junction luminescent device, and the main structure of LED is a P-N junction. Under a forward bias, the P-N junction emits visual light or infrared light
Data Source
AI summary
Epitaxial structure for micro light emitting diode (LED) includes, from bottom to top, a semiconductor substrate (102), an N-type electrical conductive layer (108), a N-type cladding layer (110), an active light emitting layer (114), a P-type cladding layer (118), and a P-type electrical conductive layer (120,122,124). The epitaxial structure for micro LED further includes an oxide layer (210) within the N-type cladding layer (110) and/or between the N-type electrical conductive layer (108) and the N-type cladding layer (110), and/or an oxide layer (410) within the P-type cladding layer (118) and/or between the P-type electrical conductive layer (120,122,124) and the P-type cladding layer (118). The oxide layer (210,410) is formed as an oxide ring, which effectively increases the PN junction current density and the light emission efficiency of the LED device. A one-time or a two-time transfer fabrication process is used to form the LED device.