Partially relaxed semiconductor layer in light emitting heterostructure
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing light emitting devices, particularly deep ultraviolet LEDs, face challenges in minimizing dislocation density and crack formation in semiconductor layers, which affects efficiency, as current methods struggle to achieve uniform composition and control stress in epitaxially grown nitride-based semiconductor layers.
Innovation Solution
Incorporating a partially relaxed semiconductor layer as a sublayer in the contact semiconductor layer of a light emitting heterostructure, along with a dislocation blocking structure, to reduce defects such as cracks and threading dislocations, by selectively growing layers with tensile or compressive residual stress and using a dislocation blocking structure with alternating tensile and compressive sublayers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If epitaxially grown nitride-based semiconductor layers are used in light emitting devices, then the device can achieve light emission function, but dislocation density and crack formation increase, reducing device efficiency
Solution Approach 1:
The contact semiconductor layer is segmented into multiple sublayers with different stress states (tensile, compressive, and partially relaxed). This segmentation allows each sublayer to perform specific functions: tensile sublayers suppress crack propagation, compressive sublayers suppress dislocation propagation, and partially relaxed sublayers provide transition zones, collectively reducing both dislocation density and crack formation while maintaining device efficiency
Solution Approach 2:
The patent creates a composite semiconductor structure by combining layers of different materials (e.g., AlGaN layers with varying aluminum compositions) and different stress states within the contact semiconductor layer. This composite approach enables simultaneous suppression of both cracks and dislocations, resolving the contradiction between maintaining light emission function and reducing defect density
2Object-generated harmful factors
If stress control methods are applied to reduce dislocation density, then defect propagation is suppressed, but the structural complexity and manufacturing difficulty increase
Solution Approach 1:
Different sublayers within the contact semiconductor layer are assigned different local qualities (tensile stress, compressive stress, or partial relaxation) based on their specific positions and functions. This local differentiation allows each sublayer to optimally suppress specific types of defects (cracks or dislocations) while keeping the overall structure manageable through systematic design
3Reliability
If thick AlGaN epitaxial layers are grown to reduce current crowding, then current distribution improves, but strain accumulation increases leading to crack formation
Solution Approach 1:
The contact semiconductor layer is designed with dynamic stress characteristics through alternating tensile and compressive sublayers. This dynamic structure allows the layer to accommodate strain accumulation from thick AlGaN epitaxial layers by providing alternating stress zones that prevent continuous crack propagation, thereby enabling thick layers to be grown without excessive strain accumulation while maintaining improved current distribution
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 effectively reduces dislocation density and crack formation, enhancing the efficiency and transmittance of light emitting devices by preventing dislocation propagation into the light generating structure, thereby improving the overall performance of deep ultraviolet LEDs.
Implementation Method 1
a dislocation blocking structure with alternating tensile and compressive sublayers
Implementation Method 2
selectively growing layers with tensile or compressive residual stress
Data Source
AI summary
A light emitting heterostructure including a partially relaxed semiconductor layer is provided. The partially relaxed semiconductor layer can be included as a sublayer of a contact semiconductor layer of the light emitting heterostructure. A dislocation blocking structure also can be included adjacent to the partially relaxed semiconductor layer.