III-Nitride Light Emitting Device Lattice-Matched Substrate
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Solution Overview
Problem
III-nitride light emitting devices grown on sapphire or SiC substrates face strain and crystal defects due to lattice mismatch, leading to poor performance and reliability issues.
Innovation Solution
Growing III-nitride structures on substrates with a closer lattice match, such as RAO3(MO)n, where R is a trivalent cation, A is a trivalent cation, M is a divalent cation, and n is an integer ≥1, to reduce strain and improve lattice matching, allowing for thicker, high-quality III-nitride layers with reduced defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If III-nitride devices are grown on sapphire or SiC substrates, then manufacturing cost and substrate availability are improved, but lattice mismatch causes strain and crystal defects leading to poor performance and reliability
Solution Approach 1:
The patent changes the substrate parameter (lattice constant) by selecting materials from specific crystal families (perovskite, spinel, rock salt) with lattice constants within 0.5-2% of GaN, InGaN, or AlInGaN layers. This parameter optimization resolves the contradiction by finding substrates that balance availability with reduced lattice mismatch, thereby improving both manufacturability and device reliability simultaneously.
2Reliability
If III-nitride layers are grown thicker to improve device performance, then light emission quality is improved, but strain and defects increase due to lattice mismatch with conventional substrates
Solution Approach 1:
The patent changes the substrate lattice constant parameter to match III-nitride materials more closely, enabling the growth of thicker III-nitride layers without accumulating excessive strain. This allows achieving high light emission quality while maintaining low defect densities, as the reduced lattice mismatch prevents strain-induced defects even in thicker layers.
3Reliability
If a substrate with perfect lattice match to III-nitride layers is used, then strain and defects are reduced improving performance, but substrate availability and cost increase
Solution Approach 1:
The patent defines an optimized range of lattice constant parameters (within 0.5-2% of III-nitride layers) rather than requiring perfect matching. This parameter range approach identifies substrates from perovskite, spinel, and rock salt families that provide near-perfect lattice matching while maintaining reasonable availability and cost, thus resolving the contradiction between performance and manufacturability.
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 results in III-nitride devices with less strain and improved performance, enabling better light emission characteristics and reliability by minimizing defects and strain in the III-nitride layers.
Implementation Method 1
The substrate has an in-plane lattice constant asubstrate and at least one III-nitride layer in the III-nitride structure has a bulk lattice constant alayer. In some embodiments [(|asubstrate−alayer|)/asubstrate]*100% is no more than 1%.
Data Source
AI summary
A device includes a substrate (10) and a III-nitride structure (15) grown on the substrate, the III-nitride structure comprising a light emitting layer (16) disposed between an n-type region (14) and a p-type region (18). The substrate is a RA03 (MO)n where R is one of a trivalent cation: Sc, In, Y and a lanthanide; A is one of a trivalent cation: Fe (III), Ga and Al; M is one for a divalent cation: Mg, Mn, Fe (II), Co, Cu, Zn and Cd; and n is an integer≥1. The substrate has an inplane lattice constant asubstrate. At lease one III-nitride layer in the III-nitride structure has a bulk lattice constant alayer such that [(|asubstrate−alayer|)/asubstrate]*100% is no more than 1%.