UV LED Micro-Elements with Reflective Bumps
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Solution Overview
Problem
Conventional deep ultraviolet light emitting diodes suffer from low light output and high forward voltage due to light absorption in p-type and n-type ohmic contact layers, and structural limitations that restrict light emission from the sides of the light emitting elements.
Innovation Solution
The ultraviolet light emitting diode design includes micro light emitting elements with p-bumps and n-bumps that cover the sides of the elements, reflecting light back towards the substrate and increasing bump sizes to enhance heat dissipation, along with an n-type ohmic contact layer placed around the micro light emitting elements to improve current spreading and reduce forward voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional deep ultraviolet light emitting diodes use p-type and n-type ohmic contact layers, then electrical connection is achieved, but light absorption occurs reducing light output
Solution Approach 1:
The patent extracts and removes the light-absorbing p-type ohmic contact layer from the light emission path. By eliminating this layer that causes light absorption and energy loss, the design achieves higher light output while maintaining electrical connection through alternative contact structures positioned away from the optical path.
Solution Approach 2:
The patent introduces an intermediary n-type contact layer that provides electrical connection without absorbing light in the same manner as the p-type layer. This intermediary structure allows current injection while minimizing light loss, resolving the contradiction between electrical connection reliability and light output efficiency.
2Loss of energy
If conventional deep ultraviolet light emitting diodes use standard structural design, then manufacturing is simplified, but light emission from sides is restricted
Solution Approach 1:
The patent transitions from conventional planar light emission to three-dimensional light emission by enabling side emission in addition to top emission. This dimensional change allows light to escape through multiple surfaces (top and sides), significantly improving light extraction efficiency and reducing total internal reflection losses in the deep ultraviolet range.
Solution Approach 2:
The patent segments the light emitting elements into micro-scale structures that facilitate side emission. By dividing the emission surface into multiple facets including side surfaces, the design enables light to escape through different directions and surfaces, improving overall light output while managing structural complexity through modular micro-element design.
3Temperature
If conventional deep ultraviolet light emitting diodes use small bump sizes, then bonding process is simpler, but heat dissipation is insufficient
Solution Approach 1:
The patent merges multiple small bumps into a single large bump structure that spans across multiple light emitting elements. This consolidation creates a larger heat dissipation interface with the substrate, improving thermal management capability while simplifying the bonding process by reducing the number of individual bonding operations required.
Solution Approach 2:
The patent employs composite bump structures with multiple material layers optimized for both electrical connection and thermal conduction. The composite design allows the bump to serve dual functions of electrical contact and heat sinking, improving heat dissipation efficiency while maintaining manufacturability through established multi-layer deposition and bonding techniques.
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 design enhances light output and reduces forward voltage by minimizing light loss and improving current distribution across the micro light emitting elements, while eliminating the need for a step difference adjustment layer in bonding processes.
Implementation Method 1
p-bumps and n-bumps that cover the sides of the elements, reflecting light back towards the substrate
Implementation Method 2
n-type ohmic contact layer placed around the micro light emitting elements to improve current spreading and reduce forward voltage
Implementation Method 3
increasing bump sizes to enhance heat dissipation
Data Source
AI summary
An ultraviolet light emitting diode is provided to comprise an n-type semiconductor layer disposed on a substrate; light emitting elements disposed on the n-type semiconductor layer, each comprising an active layer and a p-type semiconductor layer; an n-type ohmic contact layer contacting the n-type semiconductor layer around the micro light emitting elements; p-type ohmic contact layers contacting the p-type semiconductor layers, respectively; an n-bump electrically connecting to the n-type ohmic contact layer; and a p-bump electrically connected to the p-type ohmic contact layers, wherein each of the n-bump and the p-bump is disposed across over a plurality of micro light emitting elements. The micro light emitting elements may be arranged over a wide area of the substrate, and thus light output can be improved and a forward voltage may be lowered, in addition, the n-bump and the p-bump may be formed relatively widely.