Porous Semiconductor Layer Strain Management in LED Devices
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Solution Overview
Problem
Current light emitting diodes (LEDs) and laser diodes face challenges in efficiency and reliability due to defects and crack formation in semiconductor layers, which affect quantum efficiency and device performance.
Innovation Solution
A light emitting device structure is developed with a substrate, a cluster layer, a first porous semiconductor layer featuring air gaps, and a light emitting structure comprising conductive semiconductor layers, which reduces contact area and strain, preventing cracks and improving quantum efficiency through controlled growth conditions and refractive index differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional semiconductor layer structure is used, then the device structure is simple, but defects and cracks form due to strain accumulation, reducing reliability
Solution Approach 1:
The semiconductor layer is segmented into multiple sub-layers (first semiconductor layer, second semiconductor layer, third semiconductor layer) with different compositions and functions. This segmentation allows strain management through controlled dislocation propagation in specific layers while maintaining crystal quality in active regions, thereby improving device reliability without excessive complexity
Solution Approach 2:
A buffer layer is introduced as an intermediary between the substrate and the active semiconductor layers. This buffer layer acts as a mediator that accommodates lattice mismatch and strain, preventing crack formation in the active layers while allowing the device structure to remain relatively simple
2Strength
If the contact area between semiconductor layers is increased, then structural stability improves, but strain accumulation increases leading to crack formation
Solution Approach 1:
Different regions of the semiconductor layer structure are given different local qualities - the buffer layer has properties optimized for strain accommodation, while the active semiconductor layers have properties optimized for light emission. This local differentiation allows the structure to be stable without uniform strain distribution, preventing cracks
Solution Approach 2:
The problem of strain accumulation in the lateral dimension is addressed by introducing a vertical dimension solution - stacking multiple semiconductor layers with progressively relaxed strain. This dimensional transition allows strain management without increasing lateral contact area, maintaining structural stability while preventing cracks
3Reliability
If quantum efficiency is improved through better material quality, then light emission performance increases, but manufacturing precision requirements increase
Solution Approach 1:
The buffer layer is prepared in advance with specific composition gradients and thickness profiles that pre-accommodate strain before the active semiconductor layers are grown. This preliminary action reduces the precision requirements for subsequent active layer growth, as the strain management is already established, allowing high quantum efficiency with manageable manufacturing precision
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 solution enhances both internal and external quantum efficiency, reduces defects, and improves the reliability of light emitting devices by minimizing crack formation and current concentration, leading to improved performance and electric characteristics.
Implementation Method 1
improving quantum efficiency through controlled growth conditions and refractive index differences
Data Source
AI summary
A light emitting device includes a plurality of clusters spread on a surface of a substrate and a first semiconductor layer provided over the plurality of clusters. The first semiconductor layer may includes air gaps above the plurality of clusters. In addition, light emitting structure may include a first conductive semiconductor layer adjacent to the first semiconductor layer, an active layer on the first conductive semiconductor layer, and a second conductive semiconductor layer on the active layer.