Nitride Semiconductor Light Emitting Device With Graded In Composition
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Semiconductor light emitting devices using nitride-based III-V group compound semiconductors face challenges in achieving high light emission efficiency due to issues with carrier recombination and injection efficiency, particularly caused by piezo-electric fields generated by lattice strain in quantum well layers.
Innovation Solution
The semiconductor light emitting device incorporates a light emitting layer with a multiple quantum well structure where the In composition ratio of the barrier layers decreases and the well layers increases in a specific direction, optimizing the band structure to enhance carrier recombination and injection efficiency, thereby improving light emission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a quantum well layer with high In composition ratio is used to improve light emission efficiency, then carrier recombination efficiency is enhanced, but piezo-electric fields are generated due to lattice strain which reduces injection efficiency
Solution Approach 1:
The quantum well layer is divided into multiple sub-layers with different In composition ratios. The first quantum well layer has a higher In composition ratio to enhance light emission efficiency, while the second quantum well layer has a lower In composition ratio to reduce piezo-electric fields. This segmentation allows simultaneous optimization of both light emission and carrier injection efficiency.
Solution Approach 2:
Different regions of the light emitting layer are assigned different In composition ratios tailored to their specific functions. The first quantum well layer (closer to n-type layer) uses higher In ratio for efficient light emission, while the second quantum well layer (closer to p-type layer) uses lower In ratio to minimize strain and piezo-electric effects, optimizing carrier injection in that region.
2Productivity
If the In composition ratio is increased to improve carrier recombination, then light emission efficiency increases, but lattice strain increases causing degradation of crystallinity
Solution Approach 1:
The quantum well structure is segmented into multiple layers with graded In composition ratios. By distributing the In content across multiple layers rather than concentrating it in a single high-In layer, the lattice strain is reduced while maintaining high carrier recombination efficiency. The lower In ratio in the second quantum well layer specifically addresses crystallinity stability.
3Productivity
If a conventional quantum well structure is used to achieve high light emission, then the device structure is simple, but carrier injection efficiency is reduced due to piezo-electric fields
Solution Approach 1:
The light emitting layer is segmented into multiple quantum well layers with different In composition ratios, creating a more complex structure that resolves the contradiction between light emission efficiency and carrier injection efficiency by spatially separating the functions of high In ratio (light emission) and low In ratio (reduced piezo-electric fields).
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 configuration enhances the internal quantum efficiency and reduces operating voltage, leading to improved light emission efficiency without degrading the crystallinity of the barrier and well layers.
Implementation Method 1
issues with carrier recombination and injection efficiency, particularly caused by piezo-electric fields generated by lattice strain in quantum well layers
Data Source
AI summary
According to one embodiment, a semiconductor light emitting device includes n-type and p-type semiconductor layers containing a nitride semiconductor and a light emitting layer. The emitting layer includes a barrier layer containing III group elements, and a well layer stacked with the barrier layer and containing III group elements. The barrier layer is divided into a first portion on an n-type semiconductor layer side and a second portion on a p-type semiconductor layer side, an In composition ratio in the III group elements of the second portion is lower than that of the first portion. The well layer is divided into a third portion on an n-type semiconductor layer side and a fourth portion on a p-type semiconductor layer side, an In composition ratio in the III group elements of the fourth portion is higher than that of the third portion.