GaN-on-Si LED Fin Structures with Selective Cladding
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Solution Overview
Problem
The manufacture of light-emitting diodes (LEDs) using gallium-nitride-on-silicon (GaN-on-Si) structures is challenged by lattice and thermal mismatches, leading to stress, warping, cracks, and growth defects due to low indium solid solubility in GaN, which affects the quality and efficiency of the LEDs.
Innovation Solution
The method involves forming fin structures with doped core regions and selectively cladding them to create multiple quantum well regions with varying indium percentages, allowing for the growth of non-polar facets and reducing defects, while using low-cost substrates like Si to minimize manufacturing costs and enhance color emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If GaN is grown on Si substrate, then manufacturing cost is reduced, but lattice mismatch and thermal mismatch cause stresses, warping, and cracks
Solution Approach 1:
A buffer layer is introduced as an intermediary between the Si substrate and the GaN layer. This buffer layer mediates the lattice and thermal mismatch between the two materials, reducing stresses and preventing cracks while allowing the use of low-cost Si substrates
Solution Approach 2:
The composition of the buffer layer is optimized with specific ratios of Ga, In, and N elements. By adjusting these compositional parameters, the buffer layer's lattice constant and thermal properties are tuned to bridge the mismatch between Si and GaN, resolving the contradiction between cost and reliability
2Illumination intensity
If indium concentration is increased to achieve desired color emission, then color quality is improved, but lattice mismatch between GaN and Si increases
Solution Approach 1:
The buffer layer acts as a mediator that accommodates high indium concentrations in the GaN layer without transmitting the full lattice mismatch stress to the Si substrate. This enables high-quality color emission while maintaining structural integrity
Solution Approach 2:
The buffer layer's composition is specifically optimized to handle high indium content. By adjusting the Ga, In, and N ratios in the buffer layer, it can accommodate the lattice expansion caused by high indium concentration in the GaN layer, enabling precise color control without sacrificing manufacturing precision
3Illumination intensity
If indium concentration is increased, then color emission is improved, but solid solubility limits cause growth defects
Solution Approach 1:
The buffer layer's composition is optimized to have higher indium solubility than standard GaN. By adjusting the Ga, In, and N ratios, the buffer layer can accommodate high indium concentrations without exceeding solid solubility limits, enabling high-quality color emission without growth defects
Data Source
AI summary
The present disclosure generally relates to semiconductor structures and, more particularly, to light emitting diodes and methods of manufacture. The method includes: forming fin structures with a doped core region, on a substrate material; forming a first color emitting region by cladding the doped core region of a first fin structure of the fin structures, while protecting the doped core regions of a second fin structure and a third fin structure of the fin structures; forming a second color emitting region by cladding the doped core region of the second fin structure, while protecting the doped core regions of the first fin structure and the third fin structure; and forming a third color emitting region by cladding the doped core region of the third fin structure, while protecting the doped core regions of the first fin structure and the second fin structure.