Nitride LED with Distributed Bragg Reflector and Current-Conduction Layer
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Solution Overview
Problem
The current nitride semiconductor LEDs face issues with current crowding due to conductivity differences between metal electrodes and n-type doped nitride semiconductor layers, leading to decreased light-emitting efficiency and reliability.
Innovation Solution
A light-emitting element design incorporating a current-conduction layer with a distributed Bragg reflector to assist in current conduction and light reflection, reducing current crowding by using a p-electrode with a smaller cross-section width and a distributed Bragg reflector to replace the traditional reflective metal layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional metal electrode structure is used in nitride LED, then electrical connection is achieved, but current crowding occurs due to conductivity differences between metal and n-type doped nitride semiconductor layer
Solution Approach 1:
The patent introduces a current-conduction layer as an intermediary between the metal electrode and the n-type doped nitride semiconductor layer. This intermediate layer has conductivity that matches the semiconductor layer, serving as a mediator that prevents current crowding by providing a gradual transition in conductivity rather than a sharp interface between metal and semiconductor.
Solution Approach 2:
The patent changes the conductivity parameter of the electrode structure by introducing a current-conduction layer with specific conductivity characteristics that match the n-type doped nitride semiconductor layer. This parameter adjustment ensures uniform current distribution by eliminating the conductivity mismatch that causes current crowding.
2Ease of manufacture
If the sapphire substrate is used in original LED chip structure, then crystal growth is facilitated, but heat dissipation is poor due to low heat conductivity
Solution Approach 1:
The patent inverts the traditional LED chip structure, placing the sapphire substrate at the light-emitting surface rather than at the bottom. This inversion allows the high-rigidity sapphire substrate to serve as a light transmission window while the heat dissipation function is transferred to the package substrate, which has superior thermal conductivity.
Solution Approach 2:
The patent extracts the heat dissipation function from the sapphire substrate by inverting the chip structure. The sapphire substrate retains its crystal growth advantages and light transmission properties, while the heat dissipation responsibility is transferred to the package substrate, separating the optical and thermal functions.
3Reliability
If electrodes are placed in original LED chip structure, then electrical connection is provided, but light is shielded by electrodes reducing light-emitting efficiency
Solution Approach 1:
The patent inverts the chip structure so that the sapphire substrate, which is transparent to light, is positioned at the light-emitting surface. This allows light to escape through the substrate rather than being blocked by metal electrodes, significantly improving light extraction efficiency while maintaining electrical connection through the inverted electrode 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 design enhances light-emitting efficiency and reliability by minimizing current crowding and heat accumulation, improving the uniformity of current distribution and reducing positive voltage.
Implementation Method 1
a distributed Bragg reflector disposed on the first electrode and covering the exposed portion of the current-conduction layer
Implementation Method 2
a current-conduction layer disposed on the second-type semiconductor layer
Implementation Method 3
A light-emitting diode is a type of semiconductor device that emits light when voltage is applied to it
Data Source
AI summary
A light-emitting element is provided, including: a light-emitting unit sequentially comprising a first-type semiconductor layer, a light-emitting layer and a second-type semiconductor layer, wherein the light-emitting unit has an opening through the second-type semiconductor layer and the light-emitting layer to expose a portion of the first-type semiconductor layer; a current-conduction layer disposed on the second-type semiconductor layer; a first electrode disposed on the current-conduction layer and exposing a portion thereof; a distributed Bragg reflector disposed on the first electrode and covering the exposed portion of the current-conduction layer; and a second electrode disposed on the distributed Bragg reflector and filling the opening to electrically connect to the first-type semiconductor layer.