InGaN Light Emitting Device Buffer Layer Lattice Mismatch
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Solution Overview
Problem
Current light emitting devices face challenges in achieving high light extraction efficiency and reliability due to lattice mismatch and stress in semiconductor layers, which affect the performance and longevity of the devices.
Innovation Solution
A light emitting device with a substrate having a patterned structure and a buffer layer formed under low temperature using specific materials like GaN, InN, and AlN to reduce lattice mismatch, combined with an active layer featuring a super-lattice structure composed of InGaN layers, which improves crystallinity and reduces stress, thereby enhancing light extraction efficiency and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional semiconductor layers are used without buffer layers, then device structure is simpler, but light extraction efficiency and reliability deteriorate due to lattice mismatch and stress
Solution Approach 1:
Buffer layers composed of GaN, InN, and AlN are introduced as intermediary layers between the substrate and the InGaN active layer. These buffer layers serve as a transition zone that reduces lattice mismatch and minimizes stress accumulation, thereby improving device reliability and light extraction efficiency without directly participating in light emission
Solution Approach 2:
The patent employs composite material structures including multiple buffer layers with different compositions (GaN, InN, AlN) and a super-lattice structure in the active layer. This composite approach allows optimization of each layer's properties to collectively improve crystallinity, reduce stress, and enhance overall device performance
2Reliability
If high indium content InGaN layers are used to improve light extraction efficiency, then optical efficiency improves, but stress in the active layer increases
Solution Approach 1:
The buffer layers act as stress-absorbing intermediaries that accommodate the high indium content in the InGaN active layer. By providing a graded composition transition, the buffer layers prevent stress propagation to the substrate while maintaining the high light extraction efficiency benefits of high-indium InGaN
Solution Approach 2:
The patent systematically varies the indium content and thickness parameters of the InGaN layers within the super-lattice structure to optimize the balance between light extraction efficiency and stress management. This parameter optimization allows achieving high optical performance while maintaining structural integrity
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 significantly improves light extraction efficiency and reliability by reducing stress in the active layer, leading to increased optical efficiency and prolonged device lifespan.
Implementation Method 1
a buffer layer formed under low temperature using specific materials like GaN, InN, and AlN to reduce lattice mismatch
Implementation Method 2
a light emitting diode (LED) including a semiconductor device that converts electrical energy into light
Implementation Method 3
an active layer featuring a super-lattice structure composed of InGaN layers, which improves crystallinity and reduces stress
Data Source
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AI summary
A light emitting device may include a light emitting structure that includes a first semiconductor layer, a second semiconductor layer and an active layer between the first semiconductor layer and the second semiconductor layer, wherein the active layer includes a light emitting layer adjacent to the second semiconductor layer and that includes a well layer and a barrier layer and a super-lattice layer between the light emitting layer and the first semiconductor layer, the super-lattice layer including at least six pairs of a first layer and a second layer, wherein a composition of the first layer includes indium (In) and the second layer includes indium (In), and the composition of the first layer is different from the composition of the second layer.