III-N Epitaxial Pad Structure for Low-Dislocation Nitride Layers
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Solution Overview
Problem
Current methods for producing thick III-N nitride layers with low dislocation density are costly and inefficient, particularly for large-scale industrial applications, as they require expensive substrates and complex lithographic techniques, and struggle with uniform dislocation distribution and coalescence of crystallites.
Innovation Solution
A method involving the modification of crystalline basal sections to make them more deformable during epitaxial growth, using techniques like etching and oxidation, to reduce mechanical stresses and dislocation formation, allowing for the growth of thick III-N nitride layers with reduced dislocation density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional epitaxial growth methods are used on hetero-substrates, then production cost is reduced, but dislocation density increases and uniformity deteriorates
Solution Approach 1:
The substrate surface is divided into multiple isolated pads or pillars separated by间距, allowing independent crystallite growth on each pad. This segmentation prevents dislocation propagation across the entire substrate while maintaining low production costs through standard hetero-substrate usage.
Solution Approach 2:
The pads serve as intermediary structures between the hetero-substrate and the epitaxial layer. These pads facilitate controlled crystallite nucleation and growth, acting as mediators that reduce dislocation density while enabling cost-effective production on industrial-scale substrates.
2Manufacturing precision
If homo-substrates are used for epitaxial growth, then dislocation density is reduced, but substrate availability and production scalability worsen
Solution Approach 1:
Instead of requiring entire homo-substrates, the method segments the growth process into multiple small pads on inexpensive hetero-substrates. This allows scalable production while achieving low dislocation densities comparable to homo-substrate approaches.
Solution Approach 2:
The method uses inexpensive hetero-substrates with patterned pads as disposable growth platforms. After epitaxial growth, the substrates can be removed, leaving only the high-quality epitaxial layers. This eliminates the need for expensive homo-substrates while maintaining production scalability.
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 approach significantly reduces manufacturing costs and time, achieves low dislocation densities, and enables the production of high-quality III-N material layers suitable for microelectronic and optoelectronic devices, such as LEDs and HEMTs, by facilitating rapid coalescence and minimizing defects.
Implementation Method 1
selectively modifying the basal section vis-à-vis the germination section so as to form a modified basal section having a lower rigidity than the basal section before modification. Thus, the basal section and more generally, the pad are made more easily deformable, in particular under the effect of a mechanical stress generated during the crystallite coalescence phase
Implementation Method 2
after modification of the basal section, epitaxially grow a crystallite from the top of at least some of said pads of the assembly and continue the epitaxial growth of the crystallites until coalescence of the crystallites carried by the adjacent pads of the assembly
Data Source
AI summary
A method for obtaining at least one nitride layer based upon a III-N material includes the successive steps of providing a stack having a support substrate and a plurality of pads, each pad including at least one basal section and one germination section carried by the basal section; modifying the basal section so as to form a modified basal section having a lower rigidity that the basal section before modification; and epitaxially growing a crystallite from the top of at least some of the pads of an assembly and continuing the epitaxial growth so as to form the nitride layer on pads on the assembly.