Nitride Semiconductor Light-Emitting Device with Tilted Faces
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Solution Overview
Problem
Nitride semiconductor light-emitting devices face challenges in enhancing light-extraction efficiency due to total reflection at the phase boundary, and existing methods to increase the number of planes for improved light extraction are difficult to manufacture and degrade product yield, with dry etching processes being slow and prone to electrical breakdown.
Innovation Solution
A nitride semiconductor light-emitting device is fabricated by removing parts of the nitride semiconductor layer to create tilted lateral faces and depressed grooves on the substrate, allowing for increased surface area and light extraction, using a combination of laser processing and wet etching to enhance yield without significant damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the number of planes is increased to enhance light-extraction efficiency, then light extraction is improved, but device manufacturing becomes difficult and yield degrades
Solution Approach 1:
The device is segmented into multiple planes by forming grooves and tilted lateral faces on the substrate. This segmentation increases the number of phase boundaries that can form Escape Cones, thereby improving light extraction efficiency while maintaining manufacturability through systematic structural division
Solution Approach 2:
The invention transitions from a conventional rectangular hexahedron (3 planes per face) to a multi-plane structure with grooves and tilted faces that utilize additional spatial dimensions. By creating grooves extending into the substrate and forming tilted lateral faces, the device exploits the vertical and lateral dimensions to multiply the number of light-extraction surfaces beyond the traditional six faces
2Loss of energy
If deep grooves are formed to increase surface area for light extraction, then light-extraction effect is enhanced, but dry etching process becomes slow and causes electrical breakdown
Solution Approach 1:
The invention replaces the conventional dry etching process with a wet etching process using an inductive coupling plasma reactor. This substitution maintains the ability to form deep grooves and tilted faces for enhanced light extraction while significantly improving etching speed and avoiding the electrical breakdown issues associated with dry etching
Solution Approach 2:
The invention changes the etching process parameters by switching from dry to wet etching and using inductive coupling plasma. This parameter change enables faster removal of material to create deep grooves and tilted surfaces without causing electrical breakdown, thereby improving both light extraction and manufacturing productivity
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 approach significantly enhances light-extraction efficiency while facilitating the manufacturing process, preventing electric current concentration and enabling wider light emission within the nitride semiconductor layer, thereby improving device output and yield.
Implementation Method 1
removing parts of the nitride semiconductor layer to create tilted lateral faces and depressed grooves on the substrate, allowing for increased surface area and light extraction, using a combination of laser processing
Implementation Method 2
using a combination of laser processing and wet etching to enhance yield without significant damage
Implementation Method 3
the part of the light exceeding the critical angle (θc) undergoes total reflection on the phase boundary of the device and the light is not extracted to the exterior
Data Source
AI summary
A nitride semiconductor light-emitting device includes a substrate, a nitride semiconductor layer incorporating therein a first electroconductive semiconductor layer, a light-emitting layer and a second electroconductive semiconductor layer, a transparent electrode contiguous to at least part of a first surface of the second electroconductive semiconductor layer, and a second electrode contiguous to the first electroconductive semiconductor layer; wherein the substrate has a first surface thereof provided with a first region exposed by removal of a first part of the nitride semiconductor layer in a peripheral part of the device and a second region exposed by removal of at least a second part of the nitride semiconductor layer contiguous to the transparent electrode except the peripheral part of the device till the substrate. A method for the production of the device includes removing a first part of the nitride semiconductor layer in a peripheral part of the device till the substrate is exposed to form a first exposed region thereof and removing at least a second part of the nitride semiconductor layer contiguous to the transparent electrode except the peripheral part of the device till the substrate is reached to form a second exposed region thereof, wherein the steps are taken by combining the removal with a laser and the removal by wet etching.