Semiconductor Light Emitting Device with Multi-Level Uneven Structures
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Solution Overview
Problem
Conventional semiconductor light emitting devices suffer from low light extraction efficiency due to partial reflection at the interface between high and low refractive index layers, causing trapped light within the device.
Innovation Solution
A semiconductor light emitting device with multiple uneven structures is manufactured by forming a first uneven structure on a substrate, followed by a sacrificial layer and a metal cluster mask, which is then etched to create a second uneven structure, allowing for enhanced light extraction through the formation of nano-scale patterns and air gaps, thereby increasing the device's light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a flat interface structure is used between high and low refractive index layers, then the device structure is simple and easy to manufacture, but light extraction efficiency is poor due to partial reflection at the interface
Solution Approach 1:
The interface between the high refractive index sapphire substrate and the low refractive index air layer is segmented into multiple uneven surfaces at different levels. This segmentation creates multiple light extraction interfaces, allowing light to escape at various angles and positions, thereby reducing reflection losses and improving light extraction efficiency while maintaining manufacturing simplicity through the etching process
Solution Approach 2:
The invention transitions from a two-dimensional flat interface to a three-dimensional multi-level uneven structure. By creating depth variations in the substrate surface, light paths are altered and multiple extraction opportunities are provided, converting a simple planar interface into a volumetric light management structure that enhances extraction without complicating the manufacturing process
2Loss of energy
If photolithography or nano-imprinting processes are used to form uneven structures, then light extraction efficiency is improved, but manufacturing cost increases significantly
Solution Approach 1:
The invention replaces complex photolithography or nano-imprinting mechanical systems with a simpler wet etching process. Instead of using expensive photoresist coating, patterning, and development equipment, the patent uses chemical etching with selective etchants to directly form the multi-level uneven structures, dramatically reducing manufacturing cost while achieving the same light extraction enhancement
Solution Approach 2:
The invention changes the manufacturing approach from physical/mechanical patterning methods to chemical etching parameters. By controlling etching time, temperature, and etchant concentration, the multi-level structures are formed with precise dimensional control, achieving high light extraction efficiency through parameter optimization rather than complex equipment
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 multiple uneven structures effectively enhance light extraction efficiency by reducing trapped light within the device, improving the radiated light output without the need for costly photolithography or nano-imprinting processes.
Implementation Method 1
The aggregating of the metal layer may be performed by subjecting the metal layer to a thermal treatment. The thermal treatment is conducted under a temperature condition of between 300° C. to 650° C.
Implementation Method 2
The etching of the sacrificial layer may be performed by using a wet etching process. The wet etching process may form an additional uneven structure in the substrate.
Implementation Method 3
a first uneven structure formed in the first main surface of the substrate and comprising convex portions; a second uneven structure formed in the first main surface of the substrate and having a size smaller than that of the first uneven structure, the second uneven structure being irregular in size and interval
Data Source
AI summary
Disclosed are a semiconductor light emitting device and a method of manufacturing the same. The method includes providing a substrate having first and second main surfaces opposing each other and forming a first uneven structure in the first main surface, forming a sacrificial layer on the first main surface of the substrate, forming a mask having open regions on the sacrificial layer so as to expose a portion of an upper surface of the sacrificial layer, forming a second uneven structure in the substrate by etching the sacrificial layer and the substrate through the open regions, removing the sacrificial layer and the mask from the substrate, and forming a light emitting stack on the first and second uneven structures of the substrate.