Boron-Modified InGaN Active Region for Strain Reduction
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Solution Overview
Problem
III-nitride light emitting devices face strain-related defects due to lattice mismatch between substrates and layers, limiting the thickness and composition of InGaN active regions, which affects device performance.
Innovation Solution
Incorporating boron into the III-nitride device layers, particularly in the active region, to reduce strain and improve performance by lattice matching and adjusting the band gap energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the thickness of the InGaN active region is increased to improve light emission, then the light emission characteristics are improved, but strain-related defects increase due to lattice mismatch
Solution Approach 1:
The patent changes the compositional parameters of the active region by incorporating boron to form BInGaN alloys. This parameter change modifies the lattice constant and strain characteristics, allowing thicker active regions to be grown without exceeding strain limits. The boron content is optimized to balance strain reduction with maintained light emission properties.
Solution Approach 2:
The patent creates a composite material system BInGaN by combining boron with indium and gallium nitride. This composite approach allows tuning of both optical and mechanical properties simultaneously, enabling the active region to achieve both sufficient thickness for good light emission and appropriate strain characteristics to minimize defects.
2Adaptability or versatility
If the indium fraction in InGaN is increased to adjust band gap energy for different wavelengths, then the wavelength range is expanded, but strain energy increases causing decomposition
Solution Approach 1:
The patent introduces boron as an additional compositional parameter to the InGaN system, creating BInGaN quaternary alloys. This allows independent optimization of band gap energy (through indium content) and strain management (through boron content), enabling broader wavelength range while maintaining layer stability against decomposition.
3Reliability
If the active region thickness is limited to reduce strain, then defect concentration is reduced, but light emission efficiency decreases
Solution Approach 1:
By changing the compositional parameters to include boron in BInGaN alloys, the patent modifies the strain characteristics per unit thickness. This allows the active region to achieve greater thickness without proportionally increasing strain, thereby maintaining low defect concentrations while improving light emission efficiency through increased active volume.
Data Source
AI summary
Embodiments of the invention include a Ill-nitride semiconductor structure comprising a light emitting region (16) disposed between an n-type region (14) and a p-type region. At least one layer in the light emitting region (18) is Bx(InyGa1-y)1-xN. In some embodiments, x is less than 14%. In some embodiments, the BN composition is selected such that the Bx(InyGa1-y)1- XN layer has the same band gap energy as a comparable InGaN layer, with a bulk lattice constant that is the same or smaller than the comparable InGaN layer.