Patterned Substrate for Group III-Nitride Growth
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing semiconductor technologies face challenges in minimizing dislocation density in semiconductor layers, particularly for deep ultraviolet light emitting diodes (DUV LEDs), which affects the efficiency of these devices.
Innovation Solution
A patterned substrate with a substantially flat top surface and stress-reducing regions, such as openings, is used to grow group III-nitride semiconductor layers with high aluminum concentration, where the root mean square roughness of the surface is less than 0.5 nanometers and the openings have a characteristic size between 0.1 microns and five microns, allowing for reduced dislocation density and stress relief.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional planar substrate growth is used, then the growth process is simple, but dislocation density remains high reducing device efficiency
Solution Approach 1:
The substrate surface is segmented into discrete patterned regions (protrusions or depressions) rather than a continuous planar surface. This segmentation allows dislocations to be confined to specific areas while maintaining large defect-free regions for device growth, thereby improving reliability without excessive complexity
Solution Approach 2:
Different regions of the substrate are given different properties: patterned regions with specific geometries (protrusions or depressions) are created to locally control dislocation behavior. The local substrate structure is optimized to either attract or repel dislocations, creating zones with tailored quality for specific functions
2Reliability
If stress-reducing patterned structures are introduced, then dislocation density decreases, but manufacturing precision requirements increase
Solution Approach 1:
The substrate is pre-patterned with stress-reducing structures before epitaxial growth begins. This preliminary action creates a prepared template that guides subsequent layer formation, allowing dislocation management to be built into the structure before the actual device layers are deposited, thereby reducing the precision demands on later manufacturing steps
Solution Approach 2:
The substrate surface parameters are changed by introducing patterned protrusions or depressions with specific geometric parameters (size, spacing, depth). These parameter changes create stress fields that influence dislocation behavior, reducing dislocation density through controlled geometric modification rather than requiring extreme surface flatness
3Reliability
If microchannel epitaxy is used to reduce dislocations, then dislocation-free layers can be grown, but the process complexity and device structure become more complicated
Solution Approach 1:
The harmful dislocations are extracted or removed from the growth region by using patterned substrate structures that confine dislocations to specific areas. The microchannel or patterned regions act as barriers that prevent dislocation propagation into the active device areas, effectively taking dislocations out of the functional regions
Solution Approach 2:
The patterned substrate structure serves as an intermediary between the dislocation-prone bulk substrate and the dislocation-free device layers. This intermediate patterned layer acts as a buffer that manages dislocation flow and prevents them from reaching the active regions, mediating the transition from defective to defect-free regions
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 approach results in improved growth of semiconductor layers with reduced dislocation density and stress, enhancing the efficiency of light emitting devices by promoting the coalescence of AlN and AlGaN layers and reducing dislocation regeneration.
Implementation Method 1
A patterned substrate with a substantially flat top surface and stress-reducing regions, such as openings, is used to grow group III-nitride semiconductor layers with high aluminum concentration
Data Source
AI summary
A device having a layer with a patterned surface for improving the growth of semiconductor layers, such as group III nitride-based semiconductor layers with a high concentration of aluminum, is provided. The patterned surface can include a substantially flat top surface and a plurality of stress reducing regions, such as openings. The substantially flat top surface can have a root mean square roughness less than approximately 0.5 nanometers, and the stress reducing regions can have a characteristic size between approximately 0.1 microns and approximately five microns and a depth of at least 0.2 microns. A layer of group-III nitride material can be grown on the first layer and have a thickness at least twice the characteristic size of the stress reducing regions.